Just polished up some 4x fired winchester 30-06 brass out of my garand and had a split case that nearly separated. About half now have palpable grooves inside with very faint bright rings. This is with careful resizing to just shorter than headspace. I might get one or two more on the ones without grooves and then will need to start over. I thought I was well stocked for the reloading hoarding crisis of 2013. At least it's not 308 brass.
HXP is on 6 firings without any signs I've noticed.
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January 27, 2013, 10:47 PM
fa la la la la, la la, la, la !
January 27, 2013, 10:50 PM
Hmm...I'm using some Win brass that's on number 6 and I don't have a groove yet. The rim is all tore up on them but that's about it.
January 27, 2013, 11:07 PM
Garands and M1a are hard on cases because they open up when there is residual breech pressure. The term is residual blow back effect. The mechanisms unlock when the pressure is less than the rupture strength of the case sidewall, about 600 psia. This is intended to use the gas pressure in the barrel to help push the cartridge out after unlock hence the term residual "blow back" effect.
This is also hard as heck on the cartridge as the front end of the case is still stuck to the chamber walls. That is why your cases stretch.
I lubricate my cases, and in this post you will see pictures of LC 308 that I took 23 firings in a M1a. I am current up close to ten reloads in the 700 30-06 cases I use in Garand.