I’ve been told recently that sizing and bullet seating needs to be done within a day or two of annealing because the brass will start to harden again. Am I correct to call BS on this? From what I know about heat treating metals, once it is cooled-within an hour or so for brass cases?- the metal’s structure has been rearranged and it will stay the way it is until it is cold worked again.
Working brass after annealing
- Thread starter jnknsmk
- Start date
You're correct, it DOESN't start to harden again. But, it does spring back over the next 24 hrs. or so after sizing. How much it springs back will depend on how hard or soft it is. If it's actually totally "annealed", there won't be an measurable springback and you don't want that.
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There is zero published data saying cartridge brass gets harder with time. Too many internet experts.
Not so, as I noted in many previous posts, published studies by the Frankfort Arsenal exist proving that the thermal expansion rate between copper and brass is sufficiently different so that thermal cycles during storage will cause the brass to work harden over long periods of time. Norma Cartridge claimed that their case necks were annealed to prevent the case necks from cracking for up to 10 years. Their most recent ads claim their loaded ammo has a shelf life of 15 years.
Limit the temperature extremes and it will minimize this intrinsic work hardening.
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Ante the internet grate !! Tommy Mc
I would love to see those reports. Don't know where Frankfort products are made now but the Frankfort Arsenal in Pennsylvania was closed in 1977. I would think expansion and contraction at normal room temp variation would be in the 0.0001" range or less. The bottom end of elastic deformation. The article must have stated how much hardening took place. How much was reported? If hardening took place it would be miniscule and meaningless.
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dcali
Bullet Maker
Yes.
dcali
Bullet Maker
This doesn't make sense. You'd have to thermal cycle the ammunition in an unrealistically extreme way for this to do anything at all. The difference between brass and copper is very small and bullets are too. Lead is a bit more, but even that amounts to about .0002" of expansion difference on a .30 caliber bullet with a 100 degree swing. If anything yields, I'd guess it would be the lead.
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SSchnd
Silver $$ Contributor
Agree with Damoncali, Not sure how brass would work harden itself either without 1) cold working it over and over, 2) working hardening with heat by firing it. We anneal to rearrange the metal properties (which softens the case) then work harden a little by sizing it for the next firing. Do not sweat it, anneal and use when you use. As with anything we all have opinion, I have not seen any issues annealing and leaving it for months before loading. SD's are still single digit.
There have been numerous posts about "age hardening" on this site in the past. I suggest you look them up. For some reason some refuse to believe the findings of metallurgists and cartridge manufacturers.
To the OP, this phenomena (and it requires a seated bullet) develops over an extended period of time- so no you do not have only a day or two after anneal before it hardens again. What I would do is seat bullets soon after sizing the neck.
To the OP, this phenomena (and it requires a seated bullet) develops over an extended period of time- so no you do not have only a day or two after anneal before it hardens again. What I would do is seat bullets soon after sizing the neck.
Brass is known to work harden due to repeated temperature fluctuations.
Having said that, you would need to keep the brass outside exposed to the elements for many extreme temperature cycles to get the effect.
Keeping brass indoors will have no measurable work hardening effect. The temperature fluctuation is too small.
Having said that, you would need to keep the brass outside exposed to the elements for many extreme temperature cycles to get the effect.
Keeping brass indoors will have no measurable work hardening effect. The temperature fluctuation is too small.
D-4297
Gold $$ Contributor
I've always referred to the process as "normalizing" the Brass , since you are attempting to take it back to it's original "Normal" condition , using heat to relieve the stresses induced by the firing expansion and contraction .
What I have become aware of is the time factor between Normalizing / Annealing , Sizing in the Die , and the amount of time after-ward to use a Expander . Or Not use a Expander , and the change in Diameter , or lack there-of . Also the change in Diameter of the Neck some twelve to twenty-four hours later . These differences appear to occur more consistently based on Lot variations than anything else I've seen .
Cases that were sized with a select bushing , to obtain a certain inside diameter ; without being "Expanded" appeared to hold a closer tolerance , across the group , than those that had been "Expanded". But the variation noted was only several "tenths" through a group of fifty cases . But it did note there was no consistency of increase or decrease in diameter , but a scatter effect through-out .
Cases that were sized ; and then Expanded tended to show more variation of the Inside Diameter , of up to .0005 , which can , and will cause POI changes at the target . Why this occurred ? I have no answer , but after checking these same cases Twenty four hours later , the variation had reduced itself to less than .0002 across the group . We do know that Brass does have a "Memory", so that Known must also be included in the thinking of the over-all scenario . I continue to study these issues and see how they affect over-all performance , hoping to obtain that magical process that creates that High X-count we all seek .
What I have become aware of is the time factor between Normalizing / Annealing , Sizing in the Die , and the amount of time after-ward to use a Expander . Or Not use a Expander , and the change in Diameter , or lack there-of . Also the change in Diameter of the Neck some twelve to twenty-four hours later . These differences appear to occur more consistently based on Lot variations than anything else I've seen .
Cases that were sized with a select bushing , to obtain a certain inside diameter ; without being "Expanded" appeared to hold a closer tolerance , across the group , than those that had been "Expanded". But the variation noted was only several "tenths" through a group of fifty cases . But it did note there was no consistency of increase or decrease in diameter , but a scatter effect through-out .
Cases that were sized ; and then Expanded tended to show more variation of the Inside Diameter , of up to .0005 , which can , and will cause POI changes at the target . Why this occurred ? I have no answer , but after checking these same cases Twenty four hours later , the variation had reduced itself to less than .0002 across the group . We do know that Brass does have a "Memory", so that Known must also be included in the thinking of the over-all scenario . I continue to study these issues and see how they affect over-all performance , hoping to obtain that magical process that creates that High X-count we all seek .
I’m calling total BS on this. I’ve annealed about 25-28K pieces of brass and tested the hardness immediately after annealing and up to 4 weeks later. The difference in hardness was basically immeasurable and truly amounted to the noise of the testing equipment used. Hardness is one thing, but spring back is another. Spring back can, and absolutely will change after annealing. You can lessen this spring back change with time if you always anneal first and then don’t size the brass until you are ready to load it.
Dave
Dave
^^^^ Sorry but you are wrong with your last statement above. Too many people believe this to be true, and it simply is not. If it was, myself and several others I’ve annealed brass for wouldn’t be winning with our “ruined” brass. Btw, I’m hoping I “ruin” the next batch of 6 dasher brass for my new barrel just like my current lot of 200 pieces, which have 23 firings per piece….and they continue to shoot many clean rounds even with 4585 rounds on this barrel.
Dave
6.5 forever
Silver $$ Contributor
Wow Dave that is impressive
I thought this barrel would be toast at 2500-3200 rounds, but it just continues to hammer.
Dave
You are correct brass can only work harden. Sitting around for years is not work hardening. The term ageing is incorrect. The term aging normally refers to precipitation hardening which cannot occur in a single phase alloy without any elements that can precipitate.
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