stir the pot - case clean AND stress relief?

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rkcohen
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stir the pot - case clean AND stress relief?

Post by rkcohen » Wed Feb 10, 2021 9:39 am

okay - i'm not trying to start an argument over motor oil at a nascar event here, but...

not long ago, i got a "gearhead" buddy interested in bpcr.

he had been/does the "fake" bp season hunt w/a inline rifle and pellet with sabots. and just shakes his head when i dump a charge followed by a patch and a round ball..

anyways, i was showing him some of my 45-70 brass i had pulled out from a frankford ss pin rolling drum setup.

he remarked how cool it was to get the cases AND primer pockets so clean while stress relieving the brass..

whaaat?

remember, "gearhead.."

he explained that rods were often prepped then tumbled in a similar fashion with ball bearings which eliminated surface imperfections and imparted a stress relief effect.

hmmmm.

do i hear anything from any of our smart guys reference this possibility?

Dan O
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Re: stir the pot - case clean AND stress relief?

Post by Dan O » Wed Feb 10, 2021 11:35 am

Well when my cases are clean my stress is relieved. Does that count? :D

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bpcr shooter
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Re: stir the pot - case clean AND stress relief?

Post by bpcr shooter » Wed Feb 10, 2021 2:30 pm

in cast metal having a sharp edged imperfection would lead to a crack. The cast surface is VERY rough (under a microscope), there are deep/sharp edges and polishing removes these. This is the reason behind Billet rods and forged rods. Forged you still may have a bit of clean-up but not as bad as cast. After the grind/polish one should weigh ea rod to balance the motor.

This is normally only done in high HP, run a few runs then rebuild engines. for longevity it would be best to just buy a billet rod. Kinda like the accessories for our sport......buy once, cry once!!

matt
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bruce m
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Re: stir the pot - case clean AND stress relief?

Post by bruce m » Wed Feb 10, 2021 3:06 pm

cartridge cases have been through a fair bit to draw them, combined with controlled annealing.
how does the cleaning process compare to that?
and does the process relieve, or induce, stress?
then some of us anneal as well.
a very complex thing to go into, and maybe the greymatter could be applied elsewhere for greater benefit.
like applying the basic process of working up a load rather than asking "what is a good load"?
bruce.
ventum est amicus meus

Aviator
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Re: stir the pot - case clean AND stress relief?

Post by Aviator » Wed Feb 10, 2021 6:49 pm

Extrapolation of stress relief methods from other metals to brass may result in a broken gear tooth in the gearhead's head. :roll:

John Bly
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Re: stir the pot - case clean AND stress relief?

Post by John Bly » Wed Feb 10, 2021 7:24 pm

He may be confusing the SS pins with shot peening, a process used to compress and introduce compressive stresses in steel to compensate for extension stresses.
"Perfection consists not so much in doing extraordinary things as in doing ordinary things extraordinarily well"

mdeland
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Re: stir the pot - case clean AND stress relief?

Post by mdeland » Tue Feb 16, 2021 5:52 pm

Brass cartridge cases are deferentially hardened when formed and that has to occur by heat,working (drawing process) and to some extent by mass. The head of the case never gets annealed again once completely drawn. Only the last half of the body needs to be periodically annealed to maintain accuracy and longevity.
As far as I know brass cartridge cases only go in one direction when worked and that is to harden.

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