Brass Work Hardening analysis by Alpha Munitions

[prone.life]

Interesting analysis of brass work hardening by Alpha Munitions (Brass, Reamers, etc). They track brass hardness through seven firings of their 308 offering. Eight minute fun watch.

 

[jelenko]

Seems like we could anneal after the first firing then not for awhile.

 

[9146gt]

Or do not anneal. After 5 loadings very little change.
Tom

 

[SmittyJon]

Seems like we could anneal after the first firing then not for awhile.

I've been using a set of 130 Alpha 6 mm BR cases exclusively in my IBS Score Competition rifle since late 2023. While I didn't anneal them after the 1st firing, I do so in a hot salt bath after 6-7.

They've been fired and reloaded about 15 times each. A couple were lost somewhere along the way during Matches, and a few more got mangled going into the bump die, when I lost concentration sizing them. Currently there are 126 left, and they're still going strong.

In summary ... excellent brass, less expensive than Lapua, made right here in America, and packed and shipped in a divided, hard plastic, foam padded case. Gotta love that ... right?

SJ

 

[jelenko]

Just to clarify.
My idea of annealing just after the first firing is the most work/hardening on the brass is done in the first firing, then the amount work/hardening drops down a bunch for each firing.

 

[RegionRat]

Their summary graph


Detailed neck values with some averages and deltas.


And the shoulder values with same.

 

[SKWERLZ]

Just to clarify.
My idea of annealing just after the first firing is the most work/hardening on the brass is done in the first firing, then the amount work/hardening drops down a bunch for each firing.

Yea, ideally your dies minimally work the brass but enough to yield the brass.

 

[Bottom Fodder]

Hornaday did a podcast and said they found the best accuracy on the 4th or
5th firing after annealing

 

[jds holler]

Looks to me like we might as well take our virgin brass and go plinking for the first two or three loadings -- and then get serious about load development and competition. jd

 

[Will Henry]

I think they confused the issue a bit by not differentiating between the changes from firing vs the changes from sizing. Still, it's good raw data. You just have to kind of read between the lines. WH

 

[Chris Edmondson]

One thing mentioned is if a shooter wants to bring brass back to "virgin" each firing, ostensibly because virgin brass shot the best, then annealing must be done each firing. I'm curious if annealing brings brass back to "virgin", or just to the same hardness as virgin. My experience is the first, virgin seating is very different than subsequent seating's when annealing every time.

 

[jelenko]

One thing mentioned is if a shooter wants to bring brass back to "virgin" each firing, ostensibly because virgin brass shot the best, then annealing must be done each firing. I'm curious if annealing brings brass back to "virgin", or just to the same hardness as virgin. My experience is the first, virgin seating is very different than subsequent seating's when annealing every time.

Certainly virgin brass almost for sure won't fit the chamber as well as fired and resized.

 

[Coyotefurharvester]

By their data, I would believe load development should be done after 2nd firing of brass(if not annealing). And if you anneal after the first firing, load development and subsequent loads need annealed brass to keep the tune. For consistency.

 

[Straightshooter1]

One thing mentioned is if a shooter wants to bring brass back to "virgin" each firing, ostensibly because virgin brass shot the best, then annealing must be done each firing. I'm curious if annealing brings brass back to "virgin", or just to the same hardness as virgin. My experience is the first, virgin seating is very different than subsequent seating's when annealing every time.

Yes, annealing can bring brass back to "virgin" softness, but gotta keep in mind the whole cycle of movement the brass is going through from firing to after sizing.

In my testing and I've been able to get my brass back to the virgin brass hardness. When I annealed my cases after firing, I had to anneal them to where they were actually softer than virgin brass. Then when the cases were sized, it brought the hardness to the same reading I got for the virgin brass (the virgin brass hardness reading is my target for my brass prep).

I've measured hardness of case after firing and before annealing and found not much change in hardness, though this was on cases that had already been fire formed and been fired more than twice. The biggest change in hardness came due to the sizing of the cases after my annealing process.

PS: then there's this issue of brass longevity:

 

[Straightshooter1]

By their data, I would believe load development should be done after 2nd firing of brass(if not annealing). And if you anneal after the first firing, load development and subsequent loads need annealed brass to keep the tune. For consistency.

As I've always pointed out, the big issues about annealing vs not annealing is how much is the brass being worked during the cycle of firing and sizing. If a chamber and sizing die are customized to where there's very little movement going on during this cycle, then one can do just fine without any annealing and the data from that Alpha test video supports that hypothesis. But if one has a mass produced factory chamber and likewise a sizing die where there's a lot of movement going on, then annealing can really be a benefit. Then, you have everything in-between.

 

[Straightshooter1]

Here's another annealing test for those here who may not have seen this before:

And I've compiled his data on a spread sheet for me to get a better idea of the results:

 

[akajun]

One factor they didn't/ cant test. Brass age or precipitation hardens too. think about old ammo that get split necks in storage, thats what thats from.

 

[Webster]

Interesting analysis of brass work hardening by Alpha Munitions (Brass, Reamers, etc). They track brass hardness through seven firings of their 308 offering. Eight minute fun watch.

Cannot believe they bought that hardness tester. Big bucks!

 

[Leeinmichigan]

For SR Benchrest, shooting 6ppc, her are my thoughts on this subject.
First, what is considered as Brass Failure in the charts above?
Other than loose primer pockets, I don’t know why I switch out my brass. I don’t observe performance changes. Example, at last year’s IBS group Nationals, I believe I finished 6th in the UNL 200 yards event using brass that had been loaded 20-25 times. I would have a hard time proving to myself that I would have won shooting newer brass.

 

[RegionRat]

One factor they didn't/ cant test. Brass age or precipitation hardens too. think about old ammo that get split necks in storage, thats what thats from.

Kajun, no.
What we commonly make cartridges out of is 70/30 brass and it is all one phase (alpha phase to be more specific) and that single phase brass does not precipitation harden the way other materials do.

If there were split necks on very old brass, most of the time it was due to contamination exposure to things that attacked the grain boundaries.