Scope Ring Torque Specs From Every Maker, and How to Mount a Scope
Quick answer: ring cap screws on most modern scopes get 15 to 18 inch-pounds, never more than the scope maker allows, and never by feel. Some rings are rated to 25 or 28, but the tube inside them usually is not, and the lower of the two numbers is the one you use. Base screws run 15 to 30 depending on thread and receiver. Blue thread locker goes on base screws, not on ring caps, because it lowers friction and turns 18 on the wrench into 20 to 24 on the tube. Every number a maker has published, for rings, scopes and rifles, is in the charts below with the source named. The scope ring torque specs below come from the makers' own manuals, and where two makers disagree we print both numbers instead of picking one.
We mount a lot of scopes at Redleg, and we take a lot of them back off rifles that stopped shooting. The mount is the first thing we check and the most common thing we find. This is how we do it, start to finish, the way we were taught to do it for rifles that have to shoot, and it is every torque number we could pull from the makers themselves, checked in September 2026. If the sheet in your box says something different, the sheet wins.
Why the Number Matters More Than the Feel
A scope tube is a thin aluminum shell around a set of moving parts. A ring cap screw is a small screw with a lot of mechanical advantage. The distance between clamped and crushed is a few inch-pounds, which is less than the difference between two people's idea of snug. We recently had a .243 come in that used to shoot half-MOA and was throwing shots across a sheet of paper. The rings had crushed the tube thirteen thousandths and snapped their own keepers, and the reticle was moving on its own. It did not need a barrel. It needed a torque wrench, on the day it was mounted. That story is in the post linked at the end of this one.
The other thing the number does is make the job repeatable. A rifle that was mounted to a number can be checked against that number a year later. A rifle that was mounted to a wrist cannot.
Scope Ring Torque Specs, Maker by Maker
Everyone says check the manufacturer. Almost nobody does, because it means digging a folded sheet out of a box you threw away. So we pulled the published number from every ring, scope and rifle maker we could find and put them in one place. Every figure here comes from the maker's own instruction sheet, owner's manual, or support page, checked in September 2026. Where a maker publishes nothing, the chart says so; that is a finding, not a gap. Where a number came from a dealer copy or a support email rather than the maker's own page, the chart says that too. Specs change, and the sheet in your box wins.
Three things jump out. The range is wider than most people think: 10 to 35 inch-pounds on a ring cap depending on whose ring it is, with one outlier at 55 that only applies to a different kind of clamp. The ring maker and the scope maker are often not saying the same number. And the makers disagree with each other about thread locker, out loud, which we get to further down.
What the ring and mount makers publish
Listed A to Z by maker. Find yours, then read across.
Ring or mount maker | Ring cap screws (in-lb) | Base screws or rail clamp (in-lb) | Their word on thread locker |
Aero Precision Ultralight | 15 | 15 | Non-permanent thread locker recommended |
American Defense (ADM) | 20 to 25, or the scope maker's number | GI bolt 30 to 40, never past 60 | Their Vibra-Tite VC-3 only. No Loctite anywhere, it voids the warranty |
American Rifle Co. | 55 on M-Brace and M10. One large clamp screw, not a cap screw. Do not carry this number to other rings | Rail 55 | No Loctite. They tell you to oil the threads and set the number for it |
Area 419 | 18 | Clamp 45 | Blue encouraged, not required. Never red |
Arken Halo and Rigid | 18 max, or the scope maker's number | Base 30 | Sparingly, per their scope manuals |
Badger Ordnance | No number on caps. A quarter turn past finger tight and stop. 20 on the Condition One mount | Base 15 to 18. Ring nuts 65 | Loctite on base screws. None on caps |
Blaser saddle mount | Lower ring sections max 52 (5.9 Nm) | Inner rail 26.5 (3 Nm) | Loctite 243 on all screws |
Browning X-Lock (X-Bolt) | 18 | 18 | Never overtighten any base or ring screw |
Burris | 20 on every ring they make | Base 30. Crossbolt 30 on Signature Zee, 65 on XTR. XTR Signature clamps 45 on the FAQ, 40 to 70 on the instruction sheet | Silent |
DNZ Game Reaper | 25 for a cheap scope, 30 to 35 for a good one, in their words | 30 into a steel receiver, 18 into aluminum | None anywhere. Thread locker on the long screws voids the return |
EGW | 15 max on Keystone rings. 20 on Practical rings | Mounts 20. CZ mounts 25. X-Bolt front screws 10, then all 20. Crossbolt 65 | A small amount of blue on the mounting screws, per their blog |
Geissele | 15 to 18 | Clamp up to 72 | None on caps. If you must, purple 222 only, never blue or red |
Hawke rings | 16 (1.8 Nm) | Base 30 (3.4 Nm) | Silent |
Hawkins | 20 to 25 Heavy Tactical. 25 Ultra Light and Long Range Hybrid | Crossbolt 65. Hybrid base 22 (8-40), 15 (6-48) | Check the scope maker |
Ken Farrell | 20 to 30, average 25 | Base 20 to 25. Crossbolt 50 to 60 | Silent |
LaRue | 30 on the sheet in the box. Not on their website, so treat as unconfirmed | Lever by feel | Not stated |
Leupold | 28 max on STD, Mark 4, BackCountry. 25 on PRW2 and QRW2 | Base 22 (6-48), 28 (8-40). Ruger 10/22 12 to 15. Browning X-Bolt 18. Mark 4 keeper nuts 65 | Not necessary, the screws carry a nylon patch. No oil on the threads |
March Unimount rings | 15 front, 17 rear, 18 max | Base up to 30.9 (3.5 Nm) | Silent |
MDT | 15 to 22 | Clamp 25 to 30 Premier, 65 Elite. Bases 20 to 25, or 15 to 25 with thread locker | Bases drop to the low end of the range when thread locker is used |
Midwest Industries | 20 to 25 | Lever nut set by hand | Silent |
Monstrum | 18 | Base 25 | Blue on the base. Not on the rings |
Nightforce | 25 | Base 25. Crossbolt 68 on four-screw rings, 100 on six-screw 34 mm rings | Silent. Says do not lap their rings |
Primary Arms GLx | 25 | Crossbolt 65 | Silent |
Reptilia AUS | 15, or the scope maker's number | Crossbolt 45 | Purple 222 allowed, not necessary |
Riton rings | 18 | Base nuts 45 | Silent |
Ruger 77 series integral rings | 20 | Crossbolt 30 | Silent |
Sako and Tikka Optilock | 15 to 17 | Base and clamp 45 | Not stated. Figures come from a Beretta support answer, not a published sheet |
Scalarworks LEAP | 35 max | Lever, closed by hand, no tools | Silent |
Seekins | 18 to 20 | Clamp 50 to 55 | Silent |
Sig Sauer Alpha | 25 | Rail 65 | Silent |
Spuhr | 15 to 25 (1.9 to 2.9 Nm), or the scope maker's number if it is lower | Clamp 45 (5 Nm) | Screws come waxed from the factory. Degrease and use 243 only for extreme conditions |
Swampfox Freedom mount | 10 | Base 25 | Silent |
Talley | 17 to 20 on alloy rings. 20 on steel tops, 30 on steel bottoms | Tactical locking nut 65 | Blue 242 on the receiver screws. None on ring screws. Every number they give is a dry number |
Tier-One | 17.7 (2 Nm) | 35.4 (4 Nm) | Silent |
Trijicon (Q-LOC and ring mounts) | 15 with the Q-LOC mount. 18 on their rings | Q-LOC to rail finger tight up to 30 to 38. Mount to a one-piece upper 50 | A nylon patch or a drop of medium-strength thread locker on every fastener, except where a steel insert sits in aluminum |
Unknown Munitions | 25 Premier. 30 Tikka rings | Clamp 45. Tikka clamp 55 | Blue acceptable, and included |
Vector Optics | 16 (1.8 Nm) | Base 30 (3.4 Nm) | Silent |
Vortex | 15 to 18 on every scope and ring. 12 to 15 on Viper rings | Rail clamps 20 to 50 depending on the mount | Do not use it on ring screws. It acts as a lubricant and you will over-torque |
Warne | Not published per ring. Follow the scope maker | Base 25 max on steel receivers, about 15 on aluminum. X-Bolt rail 18 | Blue on base screws. None on ring screws. Never red anywhere |
Weaver | 15 on most rings, 20 on Grand Slam, 25 on 34 mm and Precision Tactical | Base 15 (6-48), 18 (8-40). Crossbolt 25 to 65 by ring line | Blue on base screws. Optional on caps and crossbolts. Never red |
Zeiss Precision Ultralight rings | 22 on 30 mm. 25 on 34 mm | Not stated | Silent |
What the scope makers publish for the tube itself
Listed A to Z by maker.
Scope maker | Limit on the tube (in-lb) | Where it says so |
Arken | 18 on their ring pages. Scope manuals give no number | Ring and mount product pages |
Burris Fullfield IV, Signature HD, Veracity PH, XTR III, XTR Pro | None published for the tube | Scope manuals are silent. Burris rings run 20 |
Bushnell Elite Tactical DMR3, XRS3 | 15 max | Owner's manuals. Banner 2 says 13 to 15 |
Delta Optical Stryker | 15 to 16 (1.7 to 1.8 Nm) | Owner's manual, read from a mirror. Treat as unconfirmed |
Element Helix, Titan, Nexus | 15 to 18 (1.7 to 2.0 Nm), 18 max | Owner's manuals |
Hawke | 16 (1.8 Nm) | Their mounting guide and manuals |
Kahles K series | 21 (2.4 Nm) max | Owner's manual, stated twice |
Leupold VX-3HD, VX-5HD, VX-6HD, Mark 4HD, Mark 5HD | None published for the tube | Scope manuals send you to the ring instructions. Leupold's own rings run 25 to 28 |
March | 15 to 18. 17 recommended on the rear ring, 15 on the front | Their torque sheet |
Maven RS series | 18 max | Owner's manual. Above 18 may crack the tube |
Nightforce SHV, NXS, Competition | 25 | Owner's manuals. The current ATACR and NX8 manuals give no number and defer to the mount maker; older ATACR manuals said 25 |
Noblex NZ6 | 14 (1.6 Nm) max | Product page. The lowest published number we found |
Revic Acura | 18 (2 Nm), stated as a 2,800 lb clamp limit on the tube | Owner's manual |
Riton | 18 | Their FAQ |
Schmidt and Bender | 24.8 (2.8 Nm) max, 17.7 to 22 (2.0 to 2.5 Nm) is enough | Their FAQ. Wider rings need less |
Shepherd | 20 max | Rogue manual. Other Shepherd manuals defer to the ring maker |
Sightron | 15 to 20 | Their FAQ and manual |
Swarovski Z5, Z8i | 17.7 (2 Nm) max | Owner's manuals. They would rather you use a ring adhesive than more torque |
SWFA SS | 20 max | Owner's manuals, 30 mm and 1 inch |
Tangent Theta | 25 | Owner's manual, read from a dealer's copy. Treat as unconfirmed |
Tract | 18 on one page, 25 on another | Two Tract mounting guides that disagree |
Trijicon AccuPoint, Huron, Ascent, Credo, Tenmile | 18. 15 with their Q-LOC mount | Trijicon torque specifications page |
Vector Optics Continental | 16 (1.8 Nm) | Owner's manual |
Vortex, every model from Diamondback to Razor | 15 to 18 | Owner's manuals and their mounting guide. One number for the whole line |
Zero Compromise (ZCO) | 25 (2.8 Nm) max | Owner's manual |
Zeiss, Sig Sauer, Steiner, Athlon, Primary Arms, EOTech, Meopta, Leica, Minox, Nikon, Crimson Trace, US Optics | None published for the tube | Manuals give turret screw torques only and send you to the ring maker |
What the rifle makers publish for base screws
Listed A to Z by maker.
Rifle | Scope base screws (in-lb) | Thread | Note |
Benelli Lupo | 22 (2.5 Nm) | Not stated | Owner's manual |
Bergara B-14, Premier, BMR, B-14R | 25 (3 Nm) | 6-48 and 8-40, by model | Bergara torque article |
Browning X-Bolt Target, Max | 25 on the rail | Not stated | Owner's manual |
Browning X-Bolt, X-Bolt 2 (X-Lock) | 18 | Not stated | Four screws per base. Manual and Browning's own article |
CZ 600 | None published | 6-48 (Remington 700 pattern) | Owner's manual |
Fierce | None published | 8-40 | Their FAQ |
Marlin 1895 (Ruger) | 18 to 22 on the rail, T10 | Not stated | Owner's manual |
Remington 700 | None published | 6-48 standard. 8-40 on some newer rifles | Current manual has no torque or thread data |
Ruger 10/22 | 12 to 15 max | Not stated | Aluminum receiver |
Ruger American Gen II | 18, T10 | 6-48 | Owner's manual |
Ruger Hawkeye LRT, LRH | About 20 on the rail | Not stated | Owner's manual |
Ruger Hawkeye, 77 series integral rings | Ring tops 20, crossbolt 30 | No base screws | 77 series manual. The Hawkeye centerfire manual gives no number |
Sauer 404 | SUM mount clamp about 26.5 (3 Nm) | None | Owner's manual |
Savage 110, Axis | Rings 15 to 20. Base screws per the base maker | 8-40 on 110 Precision, Elite Precision, Ultralite, Tactical, Timberline, Scout and others. 6-48 on the rest and all rimfire | Savage mounting guide and base guide |
Springfield 2020 Waypoint | 25 max | 6-48 | Owner's manual |
Tikka T3x, Sako 85, 90 | No screws. Integral dovetail | None | Optilock rings 15 to 17 caps, 45 clamp, per Beretta support |
Weatherby Mark V, Vanguard | 18 bases, 17 to 20 rings | Not stated | Custom shop guidance for the mounts they use |
Winchester XPR | 25 | 8-40 | Owner's manual |
Any other rifle | 6-48: 15 to 22. 8-40: 18 to 28. Aluminum receivers: 12 to 18 | The range across the base makers above. Use the base maker's number when there is one |
The lower number wins
Here is the rule that sorts the first two charts out: the lower number wins. Spuhr, EGW, Reptilia, ADM and Arken all print some version of it on their own sheets, and every other maker would agree. A Vortex scope in Leupold rings gets 18, not 28. A Nightforce scope in Vortex rings gets 18, because the rings stop there. A Swarovski in anything gets 17.7. A scope in a Scalarworks LEAP does not get 35 unless the scope maker says it can take 35, and none of them do. If the scope maker has not published a number, the ring number is all you have, and it never hurts to go to the low end of a range. Thin-walled tubes do not get stronger because the rings could take more.
Notice which makers publish nothing for the tube. Leupold and Burris scope manuals send you to the ring instructions, and Zeiss, Sig, Steiner, Athlon, Leica and Nikon do the same. That is not a spec of infinity. It means you use the ring number and you use a wrench.
Where the makers disagree with themselves
A reference is only worth trusting if it shows you the seams. Burris says 45 inch-pounds on XTR Signature clamps in the FAQ and 40 to 70 on the instruction sheet. Nightforce printed 25 in the SHV, NXS and older ATACR manuals and left the number out of the current ATACR and NX8 manuals. Tract says 18 on one mounting page and 25 on another. Ruger gives three different front action screw numbers across three manuals, which is a story for the next post. Browning says 18 on X-Lock bases and 25 to 30 for most rifles in the same article. When you hit one of these, take the lower figure and the newer document, and check with the maker if it matters.
When Nobody Publishes a Number
Every chart above this one comes from a maker. This one does not, and it exists because of a gap almost nobody talks about. The two threads most of American gunsmithing runs on, 6-48 and 8-40, are not standard threads. They are UNS, Unified National Special. They are not UNC and they are not UNF, and they appear in none of the standard engineering fastener tables. So the general references skip them, the gun makers publish only for their own products, and a man with an older rifle and no paperwork is left guessing.
Here is our best answer. Read the next paragraph before you use it.
Read this first
This is a last resort, not a specification. If your maker publishes a figure, use theirs and ignore this chart. The charts above are the real answer and they always win.
If nobody publishes one, four rules. Start at the bottom of the row rather than the top. Know what your receiver is made of, because the same screw into aluminum takes a bit over half what it takes into steel. Count your threads, which we explain below. And stop the moment resistance stops building: if the force needed to turn the screw ever starts going down while you are still tightening, you are either stripping the threads or the head is beginning to fail. A torque wrench cannot tell you that. Your hand can.
The chart, in inch-pounds
Thread | Steel receiver | Aluminum receiver |
4-40 | 8 | 4.9 |
4-48 | 9 | 5.1 |
6-32 | 12 | 7.5 |
6-40 | 14 | 7.7 |
6-48 | 15 | about 8.5 |
8-32 | 19 | 10.8 |
8-36 | 20 | 11.0 |
8-40 | 20 | about 11.5 |
10-32 | 24 | 14.8 |
M-LOK accessory | 35 | 35 |
Where these come from. The 6-48 and 8-40 figures are published by Cameron Murphy of Murphy Precision, and the M-LOK figure is published by Magpul. The aluminum column is from NASA's installation torque tables for noncritical applications, measured into 6061-T6 with an eighth of an inch of thread engagement. The remaining steel figures are scaled from the two published anchors by the tensile stress area of each thread. Those two anchors independently agree to within eight percent, which is why we are willing to print the rest.
Two things the chart assumes, so you can judge it. In steel, the screw is usually the weak part. In aluminum, the threads in the receiver are. And it treats every gun screw as the same grade, which they are not. Gun screws run from soft blued steel to hardened alloy, and a soft screw will twist off before a steel thread ever strips. If your screws came out of a bargain bin, work up from lower than the chart says.
Count your threads, because the same screw can take 12 or 22
Leupold used to publish two numbers for the same base screw. Six or more threads of engagement got 22 inch-pounds. Fewer than six got 12. Nearly double, same screw, and the only thing that changed was how much thread was actually holding.
Threads of engagement means how many turns of thread are really biting in the hole, not the size of the screw. It is the screw length minus whatever it passes through before it reaches the receiver. A 6-48 has forty-eight threads to the inch, so each thread is about twenty thousandths deep and six of them is an eighth of an inch. That is also, as it happens, exactly the engagement NASA used for their table.
Thread | 4 threads is | 6 threads is |
4-40, 6-40, 8-40 | 0.100 in | 0.150 in |
4-48, 6-48 | 0.083 in | 0.125 in |
6-32, 8-32, 10-32 | 0.125 in | 0.188 in |
8-36 | 0.111 in | 0.167 in |
The rule we use. Fewer than about four threads holding, and we treat a steel receiver like an aluminum one and use the lower column. Short holes and blind holes are where receivers get stripped, and a screw that bottoms out before it clamps feels tight while holding nothing.
This chart is not for ring cap screws
Everything above is for screws going into a receiver or a base. A ring cap screw is a different problem. It is not limited by the thread it is turning in, it is limited by the scope tube it is closing on, and that tube is thin-walled aluminum wrapped around glass. Use your scope maker's number and your ring maker's number, take the lower of the two, and never borrow a figure from this chart for a ring cap. That is how tubes get crushed.
Thread locker changes the number
Thread locker and oil both cut friction, and a torque wrench measures friction rather than clamp load, so the same reading drives the screw harder than it would on dry threads. Redleg comes down 15 percent from the published number on any screw we put thread locker on. The thread locker section further down goes through which screws get it and which do not.
If you strip one
It is not the end of the rifle. There are two usual repairs: a threaded insert, or drilling and tapping up to the next size, which is the whole reason 8-40 exists as an upgrade to a stripped 6-48 hole. Both are bench work rather than kitchen-table work, and both are worth doing properly because the second attempt has less material to hold onto. We will write that one up on its own.
Thread Locker Changes the Torque, and Here Is by How Much
The question we get more than any other about mounting is whether to put thread locker on the screws. The short answer is base screws yes, ring cap screws no, and the reason is not superstition. It is the torque math.
A torque wrench does not measure how hard the screw is clamping. It measures how hard you are twisting, and most of that twist is spent on friction under the screw head and in the threads. On a plain dry screw roughly 85 to 90 percent of what the wrench reads goes into friction and only the last slice goes into clamp load. Put anything wet on the threads and friction drops, so the same click on the wrench turns into more clamp on the tube. Engineers write this as torque equals K times diameter times clamp load, and K is the friction factor. Dry steel runs around 0.20. Oiled runs around 0.15, which is 25 percent less torque for the same clamp, or a third more clamp at the same torque.
Blue thread locker sits in between. Henkel, who make Loctite, publish a lubricity figure on the 242 data sheet: the K value lands within plus or minus 10 percent of a phosphate-and-oil fastener. Their engineering manual charts a medium-strength thread locker at about 0.18 against 0.25 for a dry fastener, in the same neighborhood as lithium grease. So at a fixed wrench setting, blue Loctite gives you somewhere between 10 and 30 percent more clamp than the dry number the ring maker had in mind, depending on how dry the screw was to start with. Set the wrench to 18 with wet threads and the tube sees what 20 to 24 would have done dry. Most of the scope limits in the chart above are inside that window.
Henkel does not tell you to reduce torque when you use their product, and in most industrial joints the extra clamp is harmless or welcome. A scope tube is not most joints. That is why most ring makers who say anything about it say the same thing. Talley: every number they publish is a dry number, and any liquid on the threads, Loctite included, lowers friction and raises the real clamp. Vortex: do not use it on ring screws, it acts as a lubricant and you will over-torque. Warne, Weaver's scope article and Monstrum say the same. Badger and Geissele: none on caps, and Geissele adds that if you insist, purple 222 is the only grade allowed. DNZ will not take a mount back that has thread locker on it. ADM forbids Loctite outright and ships their own Vibra-Tite instead. Spuhr waxes their screws at the factory and sets their numbers for waxed screws. American Rifle Company goes the other way, tells you to oil the threads, and sets their number for oiled threads.
And then there is the other camp, which a fair chart has to show. Trijicon says every fastener gets a nylon patch or a drop of medium-strength thread locker on clean threads, except where a steel insert sits in aluminum. Blaser calls for 243 on every screw of the saddle mount. Unknown Munitions includes a bottle of blue with their rings and says it is acceptable. Huskemaw and Savage say a small amount on the rings is fine. Every one of those makers wrote their number knowing what would be on the screw. That is the common thread in both camps: the maker decided what the screw surface would be and wrote the number for it. Change the surface and the number is wrong. So use the screws that came with the rings, as they came, at the maker's number, with whatever the maker said to put on them, and nothing else.
Base screws are a different case. The base is steel or aluminum against a steel receiver, the screws are buried where you cannot see them back out, and there is no thin tube underneath to crush. Talley, Warne, Weaver, Area 419, EGW, Badger, Savage and Monstrum all recommend blue on base screws, Leupold says it is not needed because their screws come with a nylon locking patch, and everyone agrees red is never the answer on a scope mount. MDT is the one maker that puts the torque change on paper: their bases run 20 to 25 inch-pounds dry, 15 to 25 with thread locker. That is the honest way to handle it. A drop on clean, degreased base threads, torque to the maker's number or the low end of the range, and let it cure. Fixture strength comes in ten to twenty minutes, full strength in twenty-four hours, and it cures slower on aluminum and anodized parts because they are inactive metals.
One more detail from Henkel's own chart. Blue 242 and 243 are rated for fasteners from a quarter inch up to three quarters. Every screw on a scope mount, 6-48, 8-40, M3, M4, 10-32, is under a quarter inch. The grade Henkel list for that size is purple 222, low strength, made for small screws and set screws, and it comes back apart with the same T15 that put it in. Reptilia and Geissele name 222 specifically. Blue works on base screws and thousands of rifles prove it, but if you have both bottles on the bench, purple is the one the chemical company would hand you. Keep either one off polymer stocks and plastic parts; the data sheet warns about stress cracking on thermoplastics.
That is what we do at Redleg. Degreased threads, a drop on the base screws, nothing on the caps unless the scope or ring maker calls for it, an inch-pound wrench set to the lower of the two published numbers, and 15 percent off that number on any screw that got thread locker. Then a witness mark so the next person can see nothing has moved.
Units, Threads and Drivers
European makers publish in newton-meters, American makers in inch-pounds, and a few in newton-centimeters, which is the Nm figure times 100. One Nm is 8.85 inch-pounds. One foot-pound is 12 inch-pounds, which is why a foot-pound wrench has no business near a scope ring.
Nm | in-lb | Where you see it |
1.6 | 14 | Noblex tube limit |
1.8 | 16 | Hawke, Vector rings and tubes |
2.0 | 17.7 | Swarovski tube, Tier-One caps, Element and Revic tubes |
2.4 | 21 | Kahles tube |
2.5 | 22 | Benelli base screws, Schmidt and Bender comfort range top |
2.8 | 25 | Schmidt and Bender and ZCO tube max, most tactical ring caps |
3.0 | 26.5 | Blaser inner rail, Sauer SUM clamp |
3.4 | 30 | Hawke, Vector, Arken base screws |
4.0 | 35.4 | Tier-One clamp |
5.0 | 44 | Spuhr clamp |
6.2 | 55 | ARC clamp |
7.3 | 65 | Most crossbolts |
Screw sizes you will meet: 6-48 and 8-40 are the American base screw threads, the second one larger and stronger. 10-32 shows up on crossbolts. M3, M4 and M5 are the metric equivalents on European mounts and most cap screws. Drivers: T10 on many base screws, T15 on most ring caps, T20 and T25 on clamps and the bigger caps, and a half-inch or 7/16 nut on tactical crossbolts. Torx heads are on the rings for a reason; they take the torque without rounding. A hex key of the wrong size will not.
On the wrench itself: the click-type inch-pound drivers most shops use are rated to plus or minus a few percent when new. They drift with drops and with being stored under load. Back the setting off to zero when you put it away, and if it has been on the floor, check it before it goes on a scope.
What You Need Before You Start
An inch-pound torque wrench. Not foot-pounds. A foot-pound wrench cannot resolve the numbers on this page, and the gap between 15 and 25 inch-pounds is the gap between a scope that holds and a scope that goes back to the maker.
Torx and hex bits that actually fit. Most ring caps are T15 and most cross-bolts are T25, and a worn bit rounds a screw head before it ever reaches torque.
A dial indicator on a magnetic base. This is the tool that decides the job, and almost nobody outside a shop owns one. It is what tells you whether your base sits flat on your receiver or is being sprung into shape every time you tighten it.
A degreaser and clean rags. Oil under a base is why bases walk under recoil.
A bore sighter, and specifically an optical collimator rather than a laser cartridge. It shows you a grid through the scope, so you can record where the crosshair sat before you started and prove it went back where it belongs.
A reticle level that references the base rather than the turret cap. A bubble sitting on a turret tells you the turret is level, which is not the same thing as the reticle being square to the rifle.
Blue thread locker for the base screws. Not for the ring caps. The thread locker section earlier in this article explains why that line exists.
A lapping bar and compound, plus a transfer color or a drop of oil to read where the rings actually touch.
Choosing Ring Height Before You Buy Anything
The rule is the lowest rings that clear.
Set the scope in the rings and look for three clearances before you commit. The objective bell has to clear the barrel and, on a bolt gun, the front base or rail. The turret housing and the ocular bell have to clear the bolt handle through its full lift. And on a rifle with iron sights you intend to keep, the scope has to clear the rear sight. A business card of daylight is enough at each point. Metal touching metal anywhere is not a mounting job, it is a rattle waiting to happen.
Then check the other end of the problem, which is your face. Mount the rifle with your eyes shut and open them. If your cheek is off the comb and you are floating your head to find the scope, the rings are too tall. That costs you more accuracy in the field than any torque number on this page, because a head that is not in the same place every shot is a rifle that is not zeroed the same way every shot.
Two practical notes. Objective diameter drives most of this: a 40mm bell will usually sit in low rings where a 50mm or 56mm needs medium or high on the same action. And an AR needs more height than a bolt gun to begin with, because the receiver sits higher relative to the comb, which is why AR mounts are sold by height over bore rather than by low, medium and high.
The mistake worth naming: do not solve a cheek weld problem with ring height. If your face does not sit naturally behind the scope at the lowest rings that clear, the fix is a cheek riser or an adjustable comb, not taller rings. Taller rings move the scope further from the bore, which changes your holdovers at close range and makes the rifle harder to shoot offhand.
We do not publish a height chart here on purpose. Ring height is measured differently by nearly every maker, some from the base of the ring and some from the rail, so a number copied from one brand's chart will not transfer to another. Measure your own clearance with the scope in the rings, or bring the rifle and the scope to the bench and we will do it with you.
Canted Bases: When 20 MOA Helps and When It Costs You
A 20 MOA base is not an accuracy upgrade. It is a way to buy back elevation travel you are about to run out of.
A canted base is machined with a built-in slope so the scope sits pointed slightly down relative to the bore. Zero the rifle and the erector inside the scope ends up sitting lower in its range than it otherwise would, which leaves you more of the scope's internal elevation to dial upward before you hit the top of its travel. On a rifle that gets dialed to distance, that is the difference between reaching your target and running out of scope.
Who actually needs one. Shooters who dial rather than hold, and who go far enough that the scope runs out. If you hunt inside four or five hundred yards and hold on hair, a flat base is the right answer and a canted one only creates problems.
What it costs you. Everything you gain at distance you give up at the bottom. With a 20 MOA base the rifle needs more up-elevation just to zero at 100 yards, and on a scope with limited internal travel you can end up near the bottom of the erector's range at your zero, or unable to zero at 100 at all. Shorter scopes and second focal plane hunting scopes are the ones that run into this.
There is a second effect worth knowing, and it connects to step six of our procedure. An erector sitting at either extreme of its travel is where tracking stops being linear and where a scope is most likely to misbehave. A canted base moves the erector toward the middle of its range at the distances you actually shoot, which is a real benefit beyond the raw travel number. It is also why we run the tracking before committing to a mount rather than after.
The alternatives, briefly. A canted rail is the usual answer on a rifle built for it. Rings with adjustable inserts get you part of the way without changing the base. And on some rifles the honest answer is a scope with more internal elevation rather than a base that fights the one you have.
How We Mount a Scope: What We Measure, and What the Measurement Decides
Most mounting advice is a torque number and a cross pattern. That is the last five minutes of the job. Everything that decides whether the rifle holds a zero happens before a driver touches a screw, and all of it is measurement.
Here is the thinking behind it. A scope tube is a thin aluminum shell wrapped around a set of moving lenses. Rings that do not line up with each other bend that tube when you close them, and a bent tube is stressed inside whether or not it looks fine from the outside. A base that does not sit flat on the receiver does the same thing one level down, and it pulls on the action every time you tighten it. So we measure first, and what the measurement says decides what the rifle needs.
The checks, in order
1. Indicate the base. Front screws tight, then loosen and tighten each rear screw while you watch the needle. Swap ends and do it again. This is the most useful four minutes in scope mounting and hardly anyone does it.
2. Read the number, because the number picks the job. Under five ten-thousandths of an inch of movement, the base is close enough that truing it and lapping the rings will get you there. More than five ten-thousandths and lapping cannot correct it, because lapping opens a hole that is already larger than the tube. That is when we call you.
3. Strip it, degrease it, and read what the old mount left behind. Worn bluing under the front of a base means it has been squirming under recoil. Oil in the screw holes means those screws were never really tight. Both of those tell us more than the customer can.
4. Check the front base screw against the barrel thread. On a lot of actions that front hole is blind and the screw bottoms on the barrel threads before the base is ever clamped. The screw feels tight and the base is loose. We take ten to twenty thousandths off the tip and polish it, and that screw is the identifiable front screw for the life of the rifle.
5. Rings forward in their slots, then marked. Push each ring all the way forward before anything gets tightened, because that is the direction recoil drives them. One punch mark on the left of the front ring, two on the rear, the same on the caps, so every piece goes back exactly where it started.
6. Run the scope's tracking before committing to it. Elevation and windage out to the stops, back to center, turrets zeroed. If the scope is near the end of its travel, that is worth knowing while a shim or a canted base is still an easy answer, not after everything is torqued.
7. Bore sighter in, and note where the crosshair sits on the grid. The tool is an optical collimator, not the laser cartridge type. Ours is a Bushnell. A spud goes into the muzzle and the collimator head hangs on it, and when you look through the scope you see a lit grid of squares out where the target would be. Whatever square the crosshair is sitting on, write it down. That coordinate is the reference you match at the end, and it is how you prove the scope did not move while you were torquing it. A laser bore sighter puts a dot on the wall instead of a grid in your scope, which is fine for getting on paper and no use at all for this check.
8. Read where the rings actually touch. A thin coat of transfer compound in the ring bottoms, set the scope in, rock it, lift it out, and read what came off on the tube. A solid band across the ring is contact. Speckles with bare metal between them are high spots carrying the whole clamp load. It is worth doing on every job, because the two rings rarely read the same.
9. Lap to contact, and know where to stop. We lap until the ring bottoms show ninety percent contact or better, and no further. The hard stop is the ring halves themselves. They have to close on the tube with an even gap left on both sides. Lap past that and the hole is bigger than the tube, the ring will not grip, and the honest fix from there is epoxy rather than more lapping.
10. Set eye relief before anything gets torqued. With the rings snug enough to hold the scope and loose enough to slide it, get behind the rifle in the position you actually shoot from. Shut your eyes, mount the rifle the way you naturally would, then open them. A full, bright picture with no dark ring at the edge means the scope is where it belongs. If you are craning forward or pulling back to find the image, slide the scope and do it again. Most hunting scopes give you somewhere around three and a half to four inches to work with, and that window is narrower than people expect.
Two things that catch people out. On a variable, eye relief shifts as you change magnification and the eye box is tightest at the top end, so set it at maximum power and it will be forgiving everywhere below. And on anything that recoils hard, leave more room than feels right at the bench. A scope set for a comfortable seated position on a magnum is how people end up with a cut eyebrow and a flinch that takes a season to unlearn.
11. Level the reticle off the base, not off the turret cap. A bubble sitting on a turret tells you the turret is level, which is not the same thing as the reticle being square to the rifle. Level the rifle first, off the base or the rail, then bring the reticle to a plumb line hung at distance and read it through the scope at the magnification you actually shoot. Then torque in a cross pattern, several passes, to the lower of the two published numbers. Ring gaps even both sides when you are done, and a witness mark across each screw head so anyone can see at a glance whether something has moved.
A level reticle is the one thing on this list you cannot prove at the bench. Everything else here you can measure standing still. An indicator reads the base, a caliper reads the tube, a wrench reads the screw. Cant you can only prove by shooting it, and the test that proves it is the tall target test.
Hang a true vertical line on a backer at 100 yards, confirmed with a plumb bob or a level, and level the rifle rather than just the scope, because a canted rifle makes the test measure you instead of the optic. Shoot a group at the bottom of the line. Dial thirty MOA or ten mils of elevation and shoot a second group at the same aim point. If the reticle is square to the rifle, the second group climbs straight up the line. If it is off by a couple of degrees, the group walks sideways as you dial, and you spend a season blaming the wind for it. The same target reads your tracking while you are there: thirty MOA at 100 yards should move the impact about thirty inches, and what it actually moved tells you whether the turrets are honest. We wrote the whole test up, how to set the backer and how to read it both ways, in our post on zeroing a hunting rifle.
12. Prove it. Boresight, shoot it, zero it, then run the tracking once more on paper. A mount is not finished because it is tight. It is finished because it shot.
When the indicator says bed it
If the base moves more than five ten-thousandths, lapping is the wrong tool and we will tell you so before we touch anything. The fix is to bed the base to your receiver so it sits without stress, and on a rifle that has to shoot as well as it possibly can, to bed the scope into the rings as well so there is no clearance left anywhere in the optic chain. It runs three days because two of the cures happen overnight, and it is the difference between a mount that is tight and a mount that is not fighting itself.
We wrote that procedure up in full, step by step, in its own post. That is the one to read if you want to see what bedding actually involves.
Not every rifle earns it. A hunting rifle that needs to hold a two hundred yard zero through a season is well served by a trued base, rings lapped to contact and an honest torque number. The indicator goes on every base that comes through this shop either way, and we tell you what it read.
What it costs. Mounting, bore sighting and lapping the rings to contact is $200. Base bedded with the rings lapped is $375. Base bedded and the scope bedded into the rings, the full treatment, is $550. All three are labor only. Rings and bases are quoted separately, because a two piece ring set can be forty dollars and a premium one piece mount can reach four hundred.
One thing worth knowing before you buy hardware: cheap rings cost more at our bench than they saved you at the counter. The tolerances are not held, so the indicator finds more error, and the job climbs a level.
If you would rather have it done and proven, scope mounting with boresighting is on our services page, with ring lapping as an option and full bedding for the rifles that call for it. Any of it is a lot cheaper than a scope.
A Five-Minute Check You Can Do Tonight
You do not need a caliper to catch most mounting problems. With the rifle unloaded and the bolt out, grab the scope by the objective bell and push it firmly forward, back, and side to side. It should feel like part of the receiver. Any give at all is a ring or base problem. Look at the ring caps: the gap between the two halves should be the same on both sides of each ring. Run a fingernail along the tube just ahead of and behind each ring; a ridge you can feel is a tube that has been pinched. Check the witness marks, and if there are none, make some. Then, with the wrench set to the lower of the two numbers in the charts above, check each cap screw. If the wrench clicks before the screw moves, it is at or above spec. If a screw turns before the click, it was loose, and now you know why the zero walked.
You Think You Already Over-Tightened It. Is the Scope Hurt?
This is the question we get after somebody reads a torque chart for the first time, and almost nobody answers it. Here is how to find out, cheapest test first.
Start with the symptom, because a crushed scope usually does not shoot badly in one place. It shoots in a different place each time. Shoot a group, shoot another, and touch nothing in between. No turret clicks, no ring screws, no bipod change. If the point of impact walks around the target on its own while nobody has adjusted anything, something is moving that should not be, and it is either the mount or the inside of the scope.
Swap in a scope you trust
This is the fastest way to split the difference between a bad scope and a bad rifle, and it costs nothing if you own two rifles. Put a scope you know is good on the rifle and shoot it again. If the problem leaves with the old scope, it was the scope. If the problem stays, the scope was never your issue and you have been chasing the wrong thing.
Then measure the tube
Take the scope out of the rings and put a caliper or a micrometer across the tube at the spot the rings sat, then again an inch away where they never touched. A tube that has been crushed measures smaller under the rings. On the .243 we wrote up, a one inch tube read 1.0010 inches clear of the rings and 0.9880 inches where they had been. That is thirteen thousandths of crush, and the flat spot was visible without the caliper once we knew to look.
Anything you can actually measure is real damage, not cosmetic. Thirteen thousandths is extreme, and it is worth saying that a tube can be hurt with far less than that. Take the reading at several points around the circumference, not just the top, because the crush is rarely even.
Run the turrets, then prove it on paper
Run elevation and windage out to the stops in both directions and back to center, and feel for grit, binding or a spot where the clicks change character. Then prove it the only way that counts, which is on paper. Dial a known amount up and back, and a known amount left and right, and see whether the group returns to where it started. A scope that does not come back to zero has an erector problem, and the erector is what the rings squeeze.
What is cosmetic and what is not
Ring marks in the finish are normal and mean nothing on their own. Every scope that has been mounted carries them. What matters is whether the tube has changed dimension, whether the turrets move cleanly, and whether it returns to zero. A scope that tracks, returns and holds through a string is a good scope no matter how it looks under the rings.
The honest part: some damage only shows up on paper, and a scope can pass a bench inspection and still wander once it is being recoiled. If the rifle matters and you cannot settle it yourself, this is exactly what the accuracy diagnostic is for. We measure the tube, run the tracking, and put a shop scope on the rifle before anyone spends money on parts.
Frequently Asked Questions
How tight should scope ring screws be?
Check the ring maker and the scope maker, and use the lower of the two numbers with an inch-pound torque wrench. For most modern scopes that is 15 to 18 inch-pounds. Some rings are rated to 25 or 28, and a few scopes allow 25, but the tube is what you are protecting. The charts in this article list every published number by maker.
What torque for scope base screws?
Use the base maker's number when there is one. Across the makers it runs 15 to 22 inch-pounds on 6-48 screws, 18 to 28 on 8-40, and 12 to 18 into aluminum receivers. Leupold says 22 and 28, Weaver says 15 and 18, Browning says 18 on X-Lock, Winchester says 25 on the XPR. A drop of blue or purple thread locker on the base screws is fine and most makers recommend it.
The scope maker and the ring maker give different torque numbers. Which one wins?
The lower one. Spuhr, EGW, Reptilia and ADM print exactly that on their instruction sheets. Vortex scopes are 15 to 18 inch-pounds regardless of what rings they sit in, Swarovski is 17.7, Bushnell Elite Tactical is 15, and Leupold rings are allowed up to 28 only because Leupold does not publish a tube limit. The rings can always take more than the tube.
Should I put Loctite on scope ring screws?
Most makers say no. Vortex, Warne, Talley, Badger, Geissele, DNZ, ADM and Monstrum all say keep it off the caps, because their torque numbers assume dry threads and thread locker lowers friction, which puts 10 to 30 percent more clamp on the tube at the same wrench setting. Trijicon, Blaser and Unknown Munitions say the opposite for their own products. Follow the maker of the rings you have.
Should I put Loctite on scope base screws?
Yes, blue or purple, a drop on clean threads, and most makers recommend it. Never red. MDT drops their base torque to the low end of the range when thread locker is used, which is the honest way to account for the friction change. Let it cure 24 hours before you shoot.
Do I reduce the torque if I use thread locker?
Yes. Redleg comes down 15 percent from the published number on any screw that gets thread locker. Henkel's own data puts blue thread locker in the same friction range as light grease, roughly 10 to 30 percent more clamp at the same reading, so the same wrench setting drives a locked screw harder than a dry one. On a base screw that extra clamp is usually harmless. On a ring cap it is the difference between the spec and a crushed tube, which is why the caps stay dry.
Blue or purple Loctite for scope screws?
By Henkel's own size chart, purple 222 is the grade for screws under a quarter inch, which is every screw on a scope mount. Blue 242 and 243 are rated for a quarter inch to three quarters. Blue works on base screws and thousands of rifles prove it; purple is the one the chemical company would hand you, and it comes apart with the same driver that put it in.
What is the difference between 6-48 and 8-40 base screws?
The number before the dash is the screw size and the number after is threads per inch. An 8-40 is larger in diameter and stronger, and it takes a higher torque, 18 to 28 inch-pounds against 15 to 22 for a 6-48. Many newer rifles and most heavy-recoil rifles are drilled 8-40. Look at the screws that came with the rifle or check the rifle chart above.
Can scope rings really crush a scope tube?
Yes. Scope tubes are thin-walled aluminum, and ring cap screws have a lot of mechanical advantage. We measured a one-inch tube at 0.988 inches under the ring and 1.001 an inch away, thirteen thousandths of crush, on a rifle whose rings had also snapped their keepers. Overtightening the caps, or tightening them onto rings that are not aligned with each other, will do it.
Do scope rings need to be lapped?
If you are not bedding them, yes, or at least checked for alignment, unless the ring maker says not to. Nightforce says lapping their rings voids the warranty and can lead to the tube slipping or crushing, because the rings are already in line. Most other rings benefit from it. Lapping trues the two rings to each other so the tube is gripped evenly instead of pinched at the edges. If you are bedding the scope into the rings, do not lap first; scuff the rings and let the epoxy make the fit, which is better than any lap can get you.
Should I bed my scope in the rings or lap the rings?
Bed it if the rifle has to shoot as well as it can. Lapping makes two rings line up with each other; bedding makes them fit the tube exactly, with no clearance and no stress, and it fixes the small misalignments that lapping cannot reach. Lapping is the right standard job and it is what most good mounts get. If you bed, do not lap first.
Why does my scope base lift when I tighten the rear screws?
Because the base and the receiver are not the same shape, and the screws are bending one to meet the other. Put a dial indicator on the base and loosen and tighten one screw at a time; a thousandth or two is normal, thirty is not, and we see both. The fix is to bed the base to the receiver so it sits without stress, then torque it. Tightening harder only bends it harder.
How do I know my scope is actually level?
A bubble level on the scope is a starting point. The tall target test is the proof: shoot at the bottom of a tall plumb line, dial up a large amount of elevation, shoot again, and see whether the second group climbed straight up the line or drifted to one side. We explain the whole test in the zeroing post.
What torque wrench do I need for scope rings?
An inch-pound wrench that covers 10 to 65 inch-pounds, with Torx bits. The click-type drivers sold for gun work are accurate enough. Not a foot-pound wrench; one foot-pound is 12 inch-pounds, and a foot-pound wrench will crush a tube before it reads anything.
What does 2 Nm equal in inch-pounds?
17.7 inch-pounds. One newton-meter is 8.85 inch-pounds. The conversion table in this article covers every figure the European makers publish.
Why do some rings say 25 or 28 inch-pounds when scope makers say 18?
Because the ring maker is rating the ring, not the tube. Leupold, Nightforce, Sig, Primary Arms and Ken Farrell rate their caps at 25 to 28; their steel or aluminum rings will take it. Whether the scope inside will is the scope maker's call, and most of them say 18 or less. That is why the lower number wins.
What happens if I over-torque scope rings?
The ring closes past where it should, the tube deforms, and the load goes somewhere. On the .243 in our shop it went into the ring keepers, which snapped. Inside the scope, a crushed tube can bind or damage the erector assembly so the reticle moves on its own and the point of impact walks around with nobody touching the turrets. The scope looks fine from outside and is broken where it counts.
How often should I check scope ring torque?
Once after the first 20 rounds, because screws seat, and then at the start of every season. With witness marks you can see at a glance whether anything moved. With a wrench set to spec, the check takes two minutes: if it clicks before the screw turns, you are at spec.
How much eye relief does a rifle scope need?
Most hunting scopes give you about three and a half to four inches, and the usable window is narrower than that sounds. Set it with the scope loose in the rings, from the position you actually shoot in, at the top of the magnification range where the eye box is tightest. On a hard recoiling rifle leave yourself more room than feels necessary at the bench.
What height scope rings do I need?
The lowest ones that clear. The objective bell has to clear the barrel and the front base, the turret housing and ocular have to clear the bolt handle through its full lift, and any iron sights you are keeping have to clear too. A business card of daylight at each point is enough. If your cheek comes off the comb to find the scope, the rings are too tall, and the fix is a cheek riser rather than taller rings.
Do I need a 20 MOA base?
Only if you dial to distance and are running out of elevation. A canted base buys back upward travel by starting the scope pointed slightly down, which matters past roughly five or six hundred yards. It costs you elevation at the bottom, so on a scope with limited internal travel you can struggle to zero at 100 yards with one fitted. If you hunt inside four hundred yards and hold rather than dial, use a flat base.
Scope mounting with boresighting, ring lapping optional, full bedding for the rifles that earn it.
Call Redleg Company at 507-677-6007, or bring it in.
430 Main Avenue, Chandler, Minnesota.
Monday to Friday, 9 to 5. Or see our services.
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