Annealing Brass: What It Is, Why People Do It, Why People Don’t — and Why Results Vary So Much
By Aaron Peterson — Founder, Hawkeye Ammosmithing
“Data-driven ballistics, tested & proven.”
“Data-driven ballistics, tested & proven.”
Author’s Note
Annealing is one of the most frequently asked about—and most argued about—subjects in precision reloading. Depending on where you look, you’ll find people who say it’s absolutely essential, people who say it’s pointless, and people who tried it once and concluded it didn’t do anything at all.This article isn’t meant to convince you that you must anneal, or that you shouldn’t. The goal here is different.
I wrote this because annealing discussions are usually fragmented, overly simplified, or framed as arguments instead of explanations. My intent is to lay out what annealing actually does, why people see such wildly different results, and how variables like brass choice, method, application, and expectations all play a role.
If you’re new to annealing, this should help you decide whether it’s worth your time. If you’re already experienced, it should help explain why others have different experiences—and hopefully introduce a few details you may not have considered.
Why Annealing Is So Polarizing
Few reloading topics generate stronger opinions than annealing. That’s because annealing often produces subtle, context-dependent results, and people tend to judge it based on their own outcome.
If someone sees clear gains in consistency or brass life, annealing becomes “essential.”
If someone sees no measurable change, annealing becomes “overhyped.”
Both conclusions can be honest—and still incomplete.
Annealing is not a magic step that guarantees better accuracy, nor is it inherently pointless. It’s a tool, and like any tool, its value depends on how it’s used, what problem it’s meant to solve, and whether the system around it is capable of revealing the benefit.
What Annealing Actually Is (and What It Isn’t)
Annealing is controlled heat treatment of the neck and shoulder area of a cartridge case to reverse work-hardening caused by firing and resizing.
The key word there is controlled.
Annealing is not:
- “Making the brass hot”
- “Getting it to glow”
- “Hitting 750°F”
This distinction—hardness vs. temperature—is the single most misunderstood part of annealing.
Temperature is only a means to an end. Hardness is the result that matters.
How and Why Brass Changes Over Time
Every time a case is fired and resized, the neck and shoulder are worked mechanically. This cold work causes brass to harden progressively.
As brass work-hardens:
- Neck springback increases
- Springback becomes less consistent
- Neck tension becomes more variable
- The brass becomes more brittle
Annealing doesn’t “fix” brass—it resets part of the work-hardening cycle, ideally returning the neck and shoulder to a predictable baseline hardness.
The Three Reasons People Anneal
1. Brass Life
Many reloaders anneal primarily to extend brass life and reduce neck splits. This can absolutely work—but results vary.
Why some people see big gains:
- Aggressive sizing
- High pressures
- Cartridges that work the neck hard
- Multiple firings on the same brass
- They already retire brass early
- Other failure modes end case life first
- Their process doesn’t stress the neck as much
2. Consistency (Neck Tension and Sizing Behavior)
This is where annealing provides its most meaningful benefit—and where expectations often go wrong.
Proper annealing helps:
- Normalize neck hardness
- Reduce springback variation
- Make sizing behavior more consistent
- Improve repeatability of neck tension
- Eliminate case volume variation
- Fix poor sizing technique
- Override inconsistent seating practices
This is also why poor annealing can be worse than no annealing at all. If the annealing step introduces more variation than it removes, the brass may actually behave less predictably.
3. Accuracy Potential
This is where most disappointment comes from.
Annealing rarely produces dramatic “before and after” group size changes. When benefits appear, they usually show up as:
- Lower ES/SD over time
- More predictable vertical at distance
- Greater stability across many firings
That doesn’t mean annealing “did nothing”—it may mean the system isn’t sensitive enough to reveal the change.
Why Results Vary So Much
Rifle and Shooter Factors
- Rifle quality
- Chamber dimensions
- Barrel condition
- Distance shot
- Shooter consistency
Loading Process Factors
Annealing does not exist in isolation.
Its effectiveness depends on:
- Sizing method (bushing vs mandrel vs expander)
- Lube consistency
- Seating method
- Neck cleanliness
- Process discipline
Annealing complements good practices—it doesn’t replace them.
Brass Variables (Often Overlooked)
This is one of the biggest reasons annealing experiences differ.
Brand Differences
Different manufacturers use:
- Different alloy batches
- Different forming processes
- Different annealing schedules
- Different neck thickness targets
Lot-to-Lot Differences
Even within the same brand, hardness and thickness can vary by lot. Annealing helps normalize brass, but it does not make inherently different brass identical.
Neck Thickness and Geometry
Thicker necks absorb heat differently than thin ones. Short-neck cartridges behave differently than long-neck cartridges. Shoulder mass affects heat flow.
This is why “one setting that works for everything” often fails.
Mixing Headstamps
Mixed brass brings mixed hardness, thickness, and springback characteristics. Annealing mixed brass does not equalize it—it often masks differences during setup and creates false confidence.
Annealing improves predictability; it does not eliminate inherent brass variation.
Hardness vs Temperature (The Core Concept)
Most reloaders lack direct hardness testing capability, so they rely on proxies:
- Tempilaq
- Color change
- Visible glow
Cartridge brass anneals based on time and temperature together, not temperature alone. Higher temperature requires less time; lower temperature requires more time.
Brass begins to glow around ~950°F. A brief glow during flash annealing does not automatically mean the brass is “dead soft.” What matters is whether the brass has entered:
- Recovery
- Recrystallization
- (Avoiding) Grain growth
Common Myths
“Brass hardens when quenched.”
That’s steel behavior, not brass. Quenching only cools brass faster.
“Any glow ruins the brass.”
Not necessarily. Duration matters as much as temperature.
“Annealing is only needed when necks split.”
Work-hardening starts long before visible failure.
“If annealing works, groups will shrink immediately.”
Effects are often cumulative and statistical, not dramatic.
Annealing Methods: What Actually Matters
Torch / Flame
Can work well when done consistently, but repeatability depends heavily on setup, flame stability, timing, and environmental factors.
Salt Bath
Provides heat and stress relief, but struggles to precisely control where and how annealing occurs without affecting the case body.
Induction
Offers excellent repeatability and efficiency by removing many flame-related variables. Results still depend on proper setup and understanding of the goal.
The “best” method is the one that produces repeatable results for your process, not the one with the strongest opinions attached to it.
How Often Should You Anneal?
There is no universal answer.
- Every 3–5 firings: common compromise
- Every firing: maximum consistency
- Never: acceptable for many applications
Anneal before sizing, not after.
Other Important Factors Worth Mentioning
- Sample size matters. Small groups and few firings can mislead.
- Carbon in necks affects bullet release. Consistency matters more than clean vs dirty.
- Cartridge design matters. Overbore and high-pressure cartridges show effects sooner.
- Time investment matters. A method that fits your workflow is more likely to be done correctly.
- Brass retirement philosophy differs. Some reloaders prefer replacement over optimization.
- Safety matters. Anneal neck and shoulder only—never the case body.
- Environment matters. Flame methods are more sensitive to airflow and lighting.
Is Annealing Worth It for You?
Likely Yes
- You chase low SD/ES
- You shoot long range
- You reuse brass extensively
- You control other variables well
- You want maximum predictability
Maybe
- You want better brass life
- You shoot moderate distances
- You value consistency but not obsessively
Probably Not
- You’re satisfied with current accuracy
- You retire brass early
- Your shooting doesn’t expose small ammo variations
- You don’t want another process step
Final Thoughts
Annealing is neither mandatory nor meaningless. It’s a tool that can reduce one source of variation—when used appropriately and consistently.
What makes annealing controversial isn’t the process itself, but the assumption that everyone should see the same result.
Understanding why results differ is far more valuable than arguing whether annealing “works.”
If this article helps you decide what makes sense for your shooting—or helps you explain annealing more clearly to someone else—then it’s done its job.
Aaron Peterson
Founder – Hawkeye Ammosmithing
Data-Driven Ballistics, Tested & Proven
Looking for a deeper technical breakdown?Founder – Hawkeye Ammosmithing
Data-Driven Ballistics, Tested & Proven
This article focuses on what annealing is, why people do it, why others don’t, and why results vary so much. For readers who want a more detailed explanation of how annealing actually works, what’s happening inside the brass, and why different methods (flame, salt bath, induction) behave differently, I’ve written a companion article titled “Annealing Brass: How It Works, What’s Actually Happening, and Why Methods Behave Differently.” It dives deeper into the stages of annealing, time vs temperature, energy delivery, and the inherent limitations and tradeoffs of each method. If you enjoy understanding the “why” behind the process—or want a more technical reference—it’s a natural next read.
Find it here:
Annealing Brass: How It Works, What’s Actually Happening, and Why Methods Behave Differently
By Aaron Peterson — Founder, Hawkeye Ammosmithing
“Data-driven ballistics, tested & proven.”
“Data-driven ballistics, tested & proven.”
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