Annealing Brass Cases: The Deep Dive

When you’re chasing precision, annealing isn’t a luxury—it’s a non-negotiable. Whether you're loading for PRS, F-Class, hunting Dall sheep at altitude, or just squeezing every bit of life from Lapua brass, proper annealing controls one of the most overlooked variables in precision shooting: neck tension.

🔬 The Why: Grain Structure & Work Hardening

Every time you fire and resize a brass case, you’re cold-working the metal—compressing and stretching it. This work-hardening makes the necks brittle over time, causing inconsistent bullet release, poor seal in the chamber, and eventually, split necks.

Brass is an alloy of copper and zinc, and its grain structure can be reset with controlled heat. That’s what annealing does—it softens the neck and shoulder, restoring flexibility while keeping the body hard.

Why the neck? Because bullet seating pressure and neck tension play a massive role in ignition consistency. Over- or under-tensioned necks can change velocity by 30-50 fps shot-to-shot, even with matched powder charges.

⚙️ The How: Precision vs. Primitive

1. AMP Annealer – Redleg’s Method

At Redleg, we use the Annealing Made Perfect (AMP) induction annealer. This machine doesn't guess—it measures and adjusts annealing parameters using real-time data and pre-programmed settings based on brass thickness.

• Temp: ~750°F at the neck/shoulder junction

• Duration: ~Varies by case brand and caliber

• Verification: Tempilaq 750° paint

Pros:

✅ No open flame

✅ Repeatability within ±5°F

✅ Doesn’t oxidize or over-soften case mouths

✅ Works without quenching—air-cooling retains grain structure without stress

Cons:

⚠️Price at $1,450–$1,600 (plus optional add-ons), it’s a big investment

⚠️Not easily tweakable by hand if you like to experiment.

Pro Tip: Use AMP’s Aztec Mode if you're working with obscure brass or wildcats. It'll analyze the metallurgy and custom-tune the program.

2. Bench-Source Annealer – Torch Control with Repeatability

The Bench-Source Vertex Annealer is a good middle ground—torch annealing without the human error. It uses a rotating aluminum wheel that indexes cases under twin torches with adjustable angles, flame height, and dwell time.

• Torches: Dual MAP or propane

• Adjustment: Micro-adjustable dwell timing from 0.1 to 10 seconds

• Rotation: Case spins during annealing for even heating

• Brass indexing: Caliber-specific wheels or universal shell holders

Our Redleg setup: Twin MAP-Pro torches at ~1" flame cones, 6.0–6.3 sec dwell for .308 Lapua brass. Tempilaq inside neck confirms neck-only heat, with body staying cool to touch.

Pros:

✅ Far more consistent than handheld torching

✅ Works with a wide range of calibers

✅ Fast for high-volume brass prep

✅ Adjustable for flame angle, case height, dwell, and flame type

Cons:

⚠️ Still susceptible to torch inconsistency if bottles get low

⚠️ Needs Tempilaq for calibration (no auto-feedback like AMP)

⚠️ Open flame = ventilation, oxidation

Redleg Pro Tip: Pre-warm the torches and keep bottles upright and full. Flame variation is the hidden gremlin in this method.

Verdict: Ideal for high-volume reloaders who want repeatable annealing without shelling out AMP-level cash. Not quite plug-and-play, but once dialed in, it’s a workhorse.

3. Torch Annealing – The Handloader’s Entry Point

You can do this with a propane torch, a drill, and a steady hand. But it’s easy to do wrong.

• Set up: Use a socket attached to a cordless drill. Stand cases upright in a pan of water (optional), spin case while heating neck/shoulder until dull red (no glowing!).

• Time: ~5–7 seconds

• Temp verification: 750°F Tempilaq inside the neck

• Cooling: Quench or air-cool — no metallurgical difference for brass, but water quench makes handling easier

Drawbacks:

⚠️ Risk of overheating body

⚠️ Non-uniform results without Tempilaq

⚠️ Flame introduces oxygen = more oxidation, more post-cleaning needed

Redleg’s Take: If you torch, use a case spinner and Tempilaq every time. Annealing without temperature control is just heat therapy for your brass.

4. Salt Bath Annealing – Clean and Uniform (But Sketchy)

Hot salt annealing uses molten salt mixtures (nitrates/nitrites) that conduct heat evenly and allow you to dip only the neck/shoulder for precise thermal targeting.

• Mix temp: 700–750°F

• Time: 5–10 seconds immersion

• Setup caution: Salts are toxic. Use PPE and proper ventilation. Keep away from moisture. Seriously.

Pros:

✅ Very even heat

✅ Great for batch annealing

✅ Minimal flame oxidation

Cons:

⚠️ High risk if mishandled

⚠️ Requires careful disposal and regular maintenance

Redleg’s Verdict: It works—but AMP or torch is easier and safer for most reloaders.

🔧 Advanced: Neck Hardness Testing

If you’re loading for ELR or pushing brass to the limits, neck hardness becomes a factor worth tracking.

• Tool: Rockwell hardness tester (HRc or HR15T scale)

• Target neck hardness: 35–40 HRc

• Too soft? Inconsistent tension, bullet creep

• Too hard? Risk of cracking, poor bullet release

  
  

  

  
  

Very few reloaders test this—but you can bet Lapua and Alpha do. This is part of why custom match ammo performs like it does.

📏 Practical Workflow (Redleg’s Bench Routine)

1. Inspect brass (length, cracks, primer pockets)

2. Sort by headstamp and weight

3. Measure water capacity (±0.1cc target)

4. Anneal with AMP Annealer

5. Lubricate

6. Full-length resize

7. Trim, deburr, chamfer

8. Neck turn if needed

9. Clean, prime, load

Final Word: Heat is Just the Beginning

Annealing isn’t about making your brass last forever—it’s about making your ammo behave consistently. Whether you're a PRS shooter running a .260 AI hot, a western hunter trying to keep your .300 PRC brass alive for another season, or a benchrest junkie chasing single-digit SDs… annealing is your edge.

At Redleg, we don’t guess—we test. Every rifle deserves ammo that matches its potential. And every reloader deserves brass that performs like it was made for that rifle. Because it was.

🔍 Annealing Method Comparison Table

Feature	AMP Annealer	Bench-Source	Torch (Manual)	Salt Bath
Heat Source	Induction coil	Dual torches (propane or MAP)	Handheld torch	Molten nitrate/nitrite salts
Precision	🔥🔥🔥🔥🔥 (±5°F)	🔥🔥🔥🔥 (very repeatable)	🔥🔥 (varies w/ hand technique)	🔥🔥🔥🔥 (very even if temp controlled)
Repeatability	Exceptional – digitally controlled	Excellent – adjustable flame/dwell time	Low – entirely manual	High – bath temp consistent
Ease of Use	Plug-and-play after setup	Easy once setup is dialed	High learning curve	Moderate – requires safety handling
Calibration	Built-in (Aztec Mode + brass profiling)	Manual – uses Tempilaq	Manual – must use Tempilaq	Manual – use thermometer or test brass
Time per Case	~6–7 sec	~6–7 sec	~5–10 sec (variable)	~5–10 sec
Speed (batch)	Medium – one case at a time	Fast – runs in sequence	Slow – fully manual	Medium – multiple cases possible
Cost (Est.)	$$$$ ($1,450–$1,600)	$$$ ($600–$750)	$ ($30–$50 setup)	$$ ($100–$200 for salts + gear)
Safety	Very safe – no open flame	Safe – but uses torches	Flame risk, burns	High caution – toxic, hot chemicals
Oxidation Risk	None – no flame	Moderate – depends on torch flame/angle	High – heavy oxidation at neck	Low – less oxidation than flame
Cleaning Required	Minimal – mostly cosmetic	Moderate – light flame residue	High – carbon, oxidation	Moderate – salt residue, needs rinsing
Best For	Match shooters, OCD brass sorters, pros	High-volume reloaders, advanced hobbyists	Beginners, budget builds	Wildcatters, batch processors, tinkerers