🔥 Primer Seating, Powder Charging & Bullet Seating — With Redleg Techniques

🔧 CHAPTER 1: PRIMER SEATING

The primer might be small, but it’s where the shot starts literally. Inconsistent primer seating can cause hangfires, erratic ignition, vertical stringing, or complete failures. Precision reloaders treat primer seating as carefully as they do bullet jump or powder charge.

🧪 1.1 Understanding Primer Pocket Fit & Tension

Brass undergoes metal fatigue after multiple firings. Every time you fire a round, the pressure inside the case tries to push the primer out, and that pocket expands microscopically. Eventually, it loses the ability to hold a primer tightly, which introduces ignition variance or even primer blowouts.

🎯 Why This Matters:

• Loose pockets reduce ignition reliability

• Increased Extreme Spread (ES) and Standard Deviation (SD)

• Higher chance of pierced or backed-out primers

🔎 1.2 Primer Pocket Gauging Go / No-Go Tools

Tools:

• 21st Century Shooting Primer Pocket Go/No-Go Gauge Set

• Short Action Customs (SAC) Primer Pocket Comparator Pins

These aren’t optional for precision reloaders they tell you whether a piece of brass is still serviceable or should be scrapped.

🧰 How It Works:

• GO Pin: If this doesn't fit, your pocket may have carbon buildup or be undersized. Uniform it.

• NO-GO Pin: If this drops in freely, the primer pocket is too loose. That piece of brass is no longer suitable for precision or hunting use.

💡 Spec:

• Large rifle primer pockets = ~0.210” dia., ~0.118"–0.122" depth

• Small rifle primer pockets = ~0.175” dia., ~0.118"–0.122" depth

🛠️ 1.3 Uniforming Primer Pockets

Uniformers don’t just clean they cut pockets to a uniform depth, ensuring the primer seats to the same depth, every time.

Tools:

• K&M Primer Pocket Uniformer (adjustable, carbide cutter)

• Sinclair Primer Pocket Uniformer

• RCBS Primer Pocket Brush (for cleaning only)

🔄 Process:

1. Insert uniformer in a drill or use by hand.

2. Cut until the tool bottoms out cleanly and evenly.

3. Check depth with a pin gauge or depth micrometer.

💡 Why it matters:

Uneven primer pockets = uneven primer seating pressure = inconsistent ignition delay.

🤏 1.4 Primer Seating Tools & Techniques

You want a primer seated:

• Fully into the pocket

• 0.003”–0.005” below flush

• With even pressure, not crushed or tilted

Tool Comparison:

Tool	Type	Notes
Competition Primer Seater Primal Rights	Bench Mount	Great feel, excellent for precision
Forster Co-Ax Bench Primer	Bench	Consistent seating depth, fast
RCBS Universal Hand Primer	Manual	Reliable, tactile, versatile
On-press priming	Progressive/single-stage	Fast but lacks precision feedback

Advanced Users: Use dial indicator setups to measure exact seating depth post-installation.

💡 Tip: Rotate your case 180° and seat again this “burnishes” the primer into the pocket and eliminates unevenness.

⚖️ CHAPTER 2: POWDER CHARGING CONSISTENCY IS KING

Powder charge weight is one of the biggest influencers of muzzle velocity and pressure. Slight inconsistencies can wreck your SD/ES and open up groups especially at long range.

💻 2.1 Using QuickLOAD: Internal Ballistics at Your Fingertips

https://quickload.co.uk/?currency=USD

QuickLOAD is a predictive modeling software that simulates:

• Chamber pressure

• Barrel time

• Muzzle velocity

• Case fill %

• Muzzle pressure

• Powder efficiency (% of powder energy converted to projectile energy)

🧠 Why You Should Use It

• Avoid pressure spikes before ever loading a round

• Fine-tune for harmonic nodes using barrel time estimates

• Pick powders based on their burn curves and consistency

• Calculate performance deltas across temperature ranges

📌 Example:

6.5 Creedmoor / 140gr ELD-M / H4350 / 26” Barrel

QuickLOAD outputs might show:

• 41.5gr = 2685 fps @ 94% fill, 48,000 PSI

• 42.5gr = 2750 fps @ 98.5% fill, 55,000 PSI

• 43.0gr = 2780 fps @ 101% fill, 59,000 PSI ← approaching pressure ceiling

This modeling helps you choose a safe, efficient load range to test with a chrono.

⚙️ 2.2 High-End Powder Dispensing Tools

Tool	Accuracy	Speed	Best For
AutoTrickler + A&D FX-120i	±0.02gr	Medium	Precision match loads
RCBS Chargemaster Supreme	±0.04gr	Fast	High-volume, hunting loads
Prometheus Gen II	±0.01gr	Slow	World-class benchrest shooters
Manual trickler + beam scale	±0.01gr	Very slow	OCD perfectionists

💡 Pro Tip: Always let your scale warm up, and weigh certified check weights to verify before your session.

🔍 2.3 Environmental Control & Best Practices

• Room temp & humidity affect powder throw

• Always keep your bench free of vibration

• Weigh every charge for ladder/OCW testing no exceptions

🎯 CHAPTER 3: BULLET SEATING EXTREME PRECISION

Once you’ve got perfect brass, primers, and powder charges, bullet seating becomes the final gateway to accuracy. This is where bullet jump tuning and alignment come into play.

📏 3.1 CBTO vs. COAL

• COAL (Cartridge Overall Length): Tip-to-base measurement

  • Less precise due to meplat inconsistencies

• CBTO (Cartridge Base to Ogive): Base to ogive (bearing surface) using a comparator

  • This is how most precision shooters tune bullet jump

💡 Use a tool like the Hornady OAL Gauge with a modified case that's been fireformed to your chamber to accurately find your rifle’s land contact point. From there, subtract your desired jump distance to determine your starting seating depth. Just be sure the case shoulder matches your resized brass for consistent results and proper chamber fit.

🔧 3.2 Seating Tools

Tool	Notes
Forster Ultra Micrometer Die	Micrometer control down to 0.001”
Redding Competition Seating Die	Floating seating stem reduces runout
Wilson Inline Seater + Arbor Press	Benchrest-level consistency

💡 Best Practice: Use bushing dies or mandrels to set consistent neck tension before seating.

📐 3.3 Measuring and Fixing Runout

Runout = bullet tilt in the neck. It causes uneven engraving into the lands and opens up groups fast.

Tools:

• 21st Century Concentricity Gauge

• Hornady Concentricity Tool

• Custom V-block and dial setup

Target Numbers:

• < 0.002” runout = precision load

• < 0.005” = acceptable for hunting

🛠️ Fixing Runout Issues

• Switch to inline seater

• Ensure your neck tension is uniform (mandrel = consistent ID)

• Polish expander balls or remove them entirely if they're dragging on the case mouth

• Use seating stems that match bullet profile a poor stem fit causes bullet tilt

📄 Download Your Reloading Data Sheets

To help you track your precision loads, velocities, seating depths, and group results, we’ve created printable Reloading Data Sheets available for free on our website.

These are the same sheets we use in-house at Redleg for:

• Ladder and OCW testing

• Tracking powder charge, COAL, CBTO, velocity, SD/ES, and group size

• Annotating conditions like temperature, wind, elevation, and barrel round count

👉 Download them here:🔗 https://www.redlegguns.com/product-page/reloading-data-sheets

Print them. Use them. Build better ammo.

🏁 Coming Up Next:

Stay tuned for Part 3 where we deep-dive into:

• Ladder Test vs. OCW Test

• Interpreting targets

• Using ES/SD vs group size for accuracy nodes

• Realistic shot diagrams with group patterns like you posted

📞 (507) 677-6007📧 info@redlegguns.com🌐 www.redlegguns.com