Load Development, Start to Finish: Ten Sessions on One Rifle
- Brandon Lolkus
- 3 days ago
- 16 min read
He never fired it.
A brand new Browning A-Bolt 3 in 6.5 Creedmoor came across the counter from a customer about twenty minutes up the road in Slayton, with a short list and one sentence: break in the barrel, mount a scope, fit a suppressor, load two hundred rounds for deer season, and make it shoot like the last one you built me.
No complaint. No problem to diagnose. A blank sheet and a deadline.
Where we started, and why we started there
We had one clue and it was a good one. His previous rifle shot Nosler Partitions well. So that is where we started, because that is what a reasonable person does. Start with what you already know works for this shooter, in this cartridge, on this game.
This rifle did not shoot them.
That sentence is the most useful thing in this article, so it is worth saying slowly. A bullet that shoots in one rifle is not a bullet that shoots in your rifle. Same cartridge, same owner, same components, same bench. Different barrel, different answer. We spent nine sessions proving it.
Then we went looking for a recipe
Getting this rifle to its number took eleven hours and twenty-seven minutes of bench time across ten separate load development sessions.
Not ten rounds. Ten sessions.
We ran it in six phases. Every phase was a controlled change, one variable moved, everything else held, and every lot number written down so we could tell later what actually caused what. Powder lot. Primer lot. Bullet lot. Brass lot. If you are not tracking lots you are not doing load development, you are guessing with a scale.
If you want to run your own workups the way we run ours, we will send you the sheet we use. [Grab the free Precision Reloading Data Sheet here.](https://www.redlegguns.com/free-reloading-sheet)
Components through the first five phases: Nosler 140 grain Partitions, CCI 200 primers, Hornady brass. The Partition is a hunting bullet with a long and completely earned reputation, and there is nothing wrong with it. It just was not what this barrel wanted.
Ten sessions, and what we were looking for in each one
Most load development articles show you the good group. Here is the whole thing, including the sessions where it fell apart and the day we threw out our best result on purpose. If you load your own ammunition, this is a template you can run on your own rifle.
Session | What we changed | What it did |
1 | Coarse charge ladder, 0.2 grain steps, six loads | Found the window |
2 | Fine ladder, 0.1 grain steps, three rounds each | Narrowed it |
3 | Three charges, five rounds each | Charge settled |
4 | Charge locked. Seating depth ladder, 0.010 inch steps | SD ranged 6.1 to 18.9 |
5 | Finer seating ladder, 0.005 inch steps | SD ranged 6.1 to 16.1 |
6 | Same window, one charge step either side | SD 4.41, ES 8.8, 0.250 inch. 0.22 MOA. |
7 | Ten round confirmation | SD 16.77, ES 43.2. It did not repeat. |
8 | Back to the session 6 load, five rounds | SD 18.66. Still no. |
9 | Same load, hot day | SD 14.29, 37 fps faster on the same charge, moderate pressure signs |
10 | Different bullet, charge down roughly 2.8 grains, seated longer | SD 7.35, ES 19.1, 0.620 inch, 0.59 MOA, no pressure signs |
Sessions one to three: finding the charge
Charge first, coarse to fine. And what we are looking for is not the smallest group. It is a velocity flat spot.
As you add powder the velocity does not climb in a straight line. There are places where you add another tenth of a grain and the speed barely moves. That plateau is where the load is least sensitive to a small error in your charge, and that is exactly what you want underneath a hunting rifle loaded on a bench in a garage and fired in November.
Find those spots on the coarse ladder. Then go to 0.1 grain steps inside them, three rounds apiece.
What breaking in a barrel means here
His list started with breaking in the barrel, so it is worth saying what that means at this bench, because it is not a fixed round count.
We break a barrel in until two things happen: it cleans up easier, and the muzzle velocity stabilizes. When the fouling comes out with less work than it did, and the speed stops climbing session over session, the barrel is done and the numbers you take off it are worth something. That is a whole subject on its own and we will write it up properly another time.
Why the round counts change, and why a new barrel lies to you
New barrels and new rifles are a lot like teenagers. They are going to lie to you.
A barrel speeds up as it gets shot early in its life. That means a velocity you record on day one is not a number you can build on. So we track our charge weights early, then come back and repeat them to see whether they are the same or whether the rifle is still gaining speed. When the numbers stop climbing, we call it leveled out. Only then is the data worth trusting.
That is why the round counts move: one, then three, then five. Early on we will sometimes shoot a few extra rounds on purpose, not for data, but to get the barrel further down the road so the data means something.
Sessions four to six: seating depth
Once the charge is settled you change one thing only. Ten thousandths of an inch at a time, then five. If you change two things at once you have learned nothing.
On this rifle we had a problem before we had a result. The bullets were seating to different depths and we had not touched the die. That is not a measurement problem, it is a friction problem, and it means the neck is gripping differently round to round.
We hold seating depth within one to two thousandths of an inch. If you cannot hold that, stop testing seating depth, because you are not testing seating depth. You are testing your case necks.
Before any of that, we measure the bullets
The box said .264. We measured these at .263.
That is not a complaint about the bullet maker, it is the reason we measure. Bullet diameter varies between makers, between designs, and sometimes between lots. Just because a box says .264 does not mean what is inside it is .264.
This matters because neck tension is the difference between the bullet and the inside of the case neck. If you assume .264 and you are actually loading .263, you just gave away a thousandth of tension and you will never see it on the scale or the calipers. You will see it on the target, as velocity that wanders for no reason you can find.
So we measured, changed the neck sizing mandrel to match what we actually had, and set the necks to give us .003 inch of tension on the bullet we were really loading. Then we taper crimped, because a light even crimp gives the bullet the same grip every round and holds seating depth once the ammunition starts getting cycled through a magazine and bounced around in a truck.
Measure your bullets. Match your mandrel to the measurement. Then go test seating depth. In that order, or you are testing one variable while another moves underneath you.
Two steps upstream of all of this have their own articles. How the brass gets sized and prepped, and how a charge actually gets weighed and thrown, both change your results before a bullet is ever seated.
Session six is what everyone is chasing. A quarter inch. An SD of 4.41. An extreme spread of under nine feet per second. On a factory hunting rifle that is an excellent number, and if we were in the business of screenshots this article would end right there.
Session seven: it did not repeat
Ten rounds through the same recipe and the standard deviation went from 4.41 to 16.77. Extreme spread from 8.8 to 43.2.
That is not a bad day at the bench. That is the load telling you the quarter inch was luck.
So we stopped loading and looked at the rifle
We had been seeing fliers. Not in every group, but in enough of them, and a flier is a different animal than a big group. A big group is usually the load. A flier is usually the rifle.
So we stopped developing and ran an accuracy evaluation on it. That is a measured look at the things that hold a rifle together: bedding contact, lug bearing, the crown, the throat, how the action actually sits in the stock. We found a few things that were not optimal, and we addressed them.
We lapped the locking lugs
The lugs at the back of the bolt are what hold everything against several tons of pressure. On a mass produced action they rarely touch the receiver evenly, and one carries most of the load. That means the bolt sits a hair differently every time it closes and the case is squeezed unevenly at the moment of firing.
Lapping is an abrasive compound and a controlled cycle until both lugs are carrying. It is not a magic trick. It is making the rifle close the same way twice.
We bedded the forearm
The A-Bolt 3 wears a synthetic stock, and synthetic stocks flex. Rest a rifle on a bag, a pack or a fence post and the forearm moves, and if it moves against the barrel your point of impact moves with it. Bedding mates the stock to the action so the two stop arguing.
The forearm bedding is the change that showed up on paper. Groups tightened, and the important part, they started repeating. That is the moment a rifle becomes worth loading for. Before that, you are developing a load for a moving target.
Sessions eight and nine: the rifle explained the rest
Two things were still wrong, and they were stacked on top of each other.
The Partitions were not seating consistently. We switched neck lube to Neolube partway through chasing it. Seating force is neck tension, and neck tension is what releases the bullet. If that varies round to round, your velocity varies round to round, and an SD bouncing between 4 and 19 is exactly what that looks like on paper.
And the charge was sitting too close to the top. Session nine ran the identical load on a hot August day and came out 37 feet per second faster, with moderate pressure signs. That is a load moving with temperature, and a load that only works when it is cool is not a hunting load. Deer season is not a controlled environment.
What SD is telling you, and when to stop chasing it
We want single digits. Nine or less. Standard deviation is how much your velocity wanders round to round, and at distance it is what opens a group vertically.
But context matters more than the number. On a hunting rifle used inside 400 yards we will give up a little SD for a smaller group that repeats. A tight group you can reproduce beats a low SD that prints wide. Know what the rifle is for before you decide which number wins.
How we read pressure, including the one we measure
Pressure signs are not a feeling. Heavy bolt lift. Primer flow. Ejector swipe. And the one that is not a judgement call: we mic the case just in front of the extractor groove. If it has grown more than half a thousandth, 0.0005 inch, we are at pressure. Often it is a combination rather than one obvious sign.
Session ten: we threw out our best group
We had a 0.250 inch group on paper. We did not use it. The ten round run failed, and that is the moment we decided the recipe was not the problem, the components were.
Different bullet, roughly two and a half grains less powder, seated longer. The Hornady 143 grain ELD-X. Different bearing surface, different length riding in the rifling, different everything about how it engages a barrel.
Five shots, not three. We do the workup on three so we are not burning barrel life proving something to ourselves, but the group that goes on a customer's card here is a five shot group, because five is what tells you whether a rifle is actually doing it.
Bigger group. Better load. A rifle that shoots six tenths every time beats a rifle that shot a quarter inch once, and the second one will cost you an animal on the one day it decides not to.
Here is the actual deciding point. We abandoned the Partition because of the seating issues, and because of those issues we could not get a consistent group out of it. We were getting good SDs and bad groups. This is a hunting rifle meant for three hundred yards and in. On that rifle the group is what matters. So we changed bullets.
That is the judgement you are paying a gunsmith for. Anyone can find a small group if they shoot enough of them. Knowing which small group to throw away is the job.
Why the recipe is not in this article
You can read charge weights off some of these targets. What you cannot read is what powder they are, and that is deliberate.
A charge weight with no powder behind it is not a recipe. It is a number. Ours came out of a current manual, a chronograph and this specific rifle, and session nine showed pressure signs at that same charge on a load that had been fine two weeks earlier. Somebody else's rifle, somebody else's lot of powder, somebody else's weather, and that number means something entirely different. Start from published data in a current manual and work up in your own rifle.
The process is the part worth sharing. The recipe belongs to the rifle it was built for.
The card that went home with the rifle
Nobody gets a group and a handshake here. Once the load was settled we chronographed it, confirmed the zero and printed the dope. 2,633 fps, 200 yard zero, Hornady 143 grain ELD-X.
Elevation is in MOA from a 200 yard zero. Positive numbers are where the bullet prints above your aiming point on the way out; negative numbers are the come ups you dial past 200. Wind is a full value crosswind at 5 and 10 mph.
Read the wind column before the elevation column. At 500 yards this rifle needs 8.69 MOA of elevation, and that is a number you dial once and forget. The same shot in a 10 mph crosswind needs 2.86 MOA of wind, and unlike elevation, that one is a judgement call every single time. Elevation is arithmetic. Wind is the part that misses.
What he ended up with
The rest of the build came together around that number.
A Leupold VX-6HD Gen 2, 3-18x44 on a 30mm tube with a CDS-ZL2 side focus and a TMOA reticle, on a Warne Vapor base and Leupold Backcountry 30mm medium rings, with a SilencerCo Scythe-Ti on the muzzle and the thread adapter to marry it up.
That last one is worth a sentence on its own. A suppressor changes point of impact, and it changes the load. Hanging a can on the end of a barrel changes barrel harmonics, the way the barrel whips as the bullet travels down it. That is not a small effect and it is not theoretical. Any load worked up without the suppressor is a different load once the suppressor is on.
Which is why the can goes on before the workup finishes, not after.
The custom dial is the other half of it. A CDS turret is cut for your specific load and your conditions, so a known distance becomes a known number of clicks instead of a hold and a hope.
What factory rifle accuracy actually depends on
There is a version of this story that ends with “so he bought a custom rifle.”
That is not what happened. He kept his rifle.
What he bought was lapped lugs, a bedded forearm, a proper optic mounted correctly, a suppressor, and a load worked up specifically for that barrel. The receiver, bolt, barrel and stock he walked in with are the receiver, bolt, barrel and stock he walked out with.
We say this every time we get a chance because it keeps being true: factory rifle accuracy is almost never limited by the barrel. It is a stock that flexes, lugs that do not bear evenly, a scope mounted to a catalog number instead of to the shooter, and ammunition the barrel does not particularly like.
Four fixable things. None of them require a new rifle.
Your turn: the short version you can run at home
1. Fix the rifle first. Bedding, lug contact, a scope mounted properly. No load fixes a stock that flexes.
2. Coarse charge ladder. Wide steps. You are hunting a velocity flat spot, not a small group.
3. Fine ladder inside the flat spot. Tenth of a grain steps, three rounds each.
4. Re-shoot your early charges. If the rifle is still speeding up, the barrel has not leveled out and your data is not real yet.
5. Lock the charge. Now move seating depth, ten thousandths then five, and hold your seating within one to two thousandths. If you cannot, fix your neck friction before you go further.
6. Watch SD and pressure together. Single digit SD is the goal. Heavy bolt lift, primer flow, ejector swipe, or more than half a thousandth of growth in front of the extractor groove means back off.
7. Confirm with a bigger group. Five rounds, then ten. If it does not repeat, it was never real.
8. Be willing to throw it out. If the components are fighting you, change the components instead of chasing the recipe.
Working through this on your own rifle and getting a result that will not repeat? Call the shop at 507-677-6007. We would rather talk you through it than watch you burn a barrel finding out.
And the honest caveat
Not every rifle does this.
Some barrels have a number and that number is an inch, and no amount of bedding or bullet swapping is going to talk them out of it. We have told customers that, in writing, on jobs where they were hoping for better news.
What we can tell you before you spend anything is which one you have got. That is what a diagnostic inspection is. We measure the throat, scope the bore, check the crown, check bedding contact, check lug bearing, and shoot it. Then you get a written report and a straight answer about whether the rifle in front of you can get where you want it to go.
Sometimes the answer is a new barrel. On this rifle it was a couple of hours of mechanical work and eleven hours of load development.
Frequently asked questions
How much can factory rifle accuracy actually improve?
This one did. 0.62 inch, 0.59 MOA, five shots at 100 yards, after lug lapping, forearm bedding and a load worked up for that specific barrel. It is not the typical result and we will not pretend it is. But an inch down to a half inch is a very common outcome on a factory hunting rifle that has never been set up properly.
What does lapping the locking lugs actually do?
It makes both lugs bear evenly against the receiver so the bolt closes in the same position every time and the case is supported evenly at the moment of firing. On most mass produced actions one lug carries most of the load out of the box.
Is bedding worth it on a synthetic stock?
Often more than on wood. Synthetic stocks flex under pressure from a bag, a pack or a bipod, and that flex moves the barrel. Bedding mates the stock to the action so the two stop moving relative to each other. On this rifle it was the single change that showed up on paper.
Why did changing the bullet make that much difference?
Different bullets have different bearing surfaces, lengths and jacket construction, and they engage the rifling differently. A barrel with a given twist and throat will genuinely shoot one bullet better than another. That is why load development tests bullets, not just powder charges.
Was there anything wrong with the Nosler Partition?
No. It is an excellent hunting bullet and it has killed a great deal of game. It just was not the bullet this particular barrel preferred. That is a rifle specific finding, not a verdict on the bullet.
How long does load development actually take?
This project ran eleven hours and twenty-seven minutes of bench time across ten sessions and six component phases. That is on the longer end, but it is not unusual. Load development is not one afternoon at the range.
Do I really need to measure bullet diameter?
Yes, and it takes seconds. We measured a box marked .264 and got .263. Bullet diameter varies by maker, by design and sometimes by lot. Since neck tension is the gap between the bullet and the inside of the neck, an assumption there quietly costs you a thousandth of tension and shows up as unexplained velocity spread.
Why do you track lot numbers?
Because the same powder from a different lot is not the same powder, and the same is true of primers and bullets. If you are not recording lots you cannot tell whether a change in the target came from your adjustment or from the components. Every phase of this project is recorded by lot.
Do I need to redo my load if I add a suppressor?
Yes, and this is the single most common thing people get wrong. A suppressor changes barrel harmonics and point of impact. A load developed without the can is a different load with the can on. We work the load up with the suppressor in place.
Why five shots instead of three?
Three shots is enough to sort through a workup without burning barrel life. Five shots is what tells you the rifle is genuinely doing it. Any rifle will eventually produce a good three shot group. The number that goes on a customer's card here is a five shot group.
What is a CDS dial and do I need one?
It is a custom elevation turret cut for your specific load and your conditions, so a known distance is a known number of clicks instead of a hold. If you hunt past about three hundred yards it removes a whole category of error. If you never shoot past two hundred, it is a nice to have.
Will you tell me if my rifle is not worth the work?
Yes, and we have. A diagnostic inspection tells you what the rifle is capable of before you spend money on it. Sometimes the honest answer is that the barrel is done.
Do you have to keep my rifle for months to do this?
No. Mechanical work is usually days. Load development takes as long as it takes and is scheduled around range conditions, because wind matters. We keep you updated as it goes rather than going quiet.
The sheet we actually use is yours, free
Everything above runs on one piece of paper. Ten sessions, six phases, every powder, primer, bullet and brass lot recorded so we could tell later what actually moved the group. That is not a talent. It is a form, filled in honestly, every single time.
It is the same data sheet we use in the shop for every custom load we build, and we will send it to you.
Get the Free Precision Reloading Data Sheet
tell us where to send it and it is on its way. No cost, and it is the fastest way to stop guessing at your own workups.
Or bring us the rifle
We do diagnostic inspections, bedding, lug lapping, suppressor work, optics mounting and load development in house, and every rifle that leaves this shop is test fired and zeroed with the numbers in writing.
See what we do https://www.redlegguns.com/services or call the shop at 507-677-6007.
Redleg Company Inc · 430 Main Ave, Chandler, MN 56122 · info@redlegguns.com
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