So I read a few online posts that 9mm reloading can be finicky and one of the things is using same headstamp brass to keep things consistent.
In .45 I didn't notice any difference between using same vs mixed headstamps.
I have a large bucket of 9mm brass that I'm in the process of tumbling and I wanted to see if those who reload 9mm separate it by headstamp, or just mix it all up.
If/when I do start reloading 9mm I plan on using the ammo for USPSA/IDPA so accuracy somewhat counts.
I reload according to brand. This is not necessary, but I do it. The main reason is that different mfg will have a slightly different powder stack height. Requires a slightly different powder cop setting.
I do re-sized the mil spec crimp primers, made by RCBS.
There is no easy way to sort the military brass out, but here are a few tips:
Winchseter military brass is usually marked WCC and a year, eg. 08. But, I have seen 9mm commercial brass marked WCC as well.
Federal/ATK is the current supplier to Uncle Sam, their military brass is marked FC and a year, eg. 08
Military brass usually has crimpled-in primers, you can tell by a ring around the primer pocket. You might want to ream out the slight amount of swaged brass from the pocket before you reload the brass.
I sort the 9mm brass to pick out:
Occasional berdan primed brass
S&B - occasional wrong pocket size
MAL (Malaysian military) - flash hole too small
Old Yugo PPU (in Cyrillic letters) - loose primer pockets
A-Merc - garbage brass in all calibers, it's all wrong
I've been reloading for close to 18 years now and the only brass I toss is Amerc. Everything else gets loaded. The only time I would separate the brass into different manufacturers would be if I was reloading for a competition or something of that nature.
Life is too short to separate out semi-auto brass in the most common calibers of 9mm, .40 and .45 by headstamp.
If it's brass, reload it.
If you run into problems with one piece of brass, take it out of the press, make a mental note of who the maker is, and keep chugging along (if you have a 550, just make sure you don't inadvertently either double charge or no charge a case by skipping a step.).
My experience has been that all A-MERC headstamped brass sucks. I have mainly noticed that with the .45's.
I can usually tell which brass sucks by how it feels when I resize/deprime it on my 550.
There is one maker of brass out there with some headstamp like "GFI" or "CFG" or something like that. The primer's are more of a copper color. When I try to deprime them I think the flash hole was made too small so it either bends or snaps a decapping rod/pin if I really force the handle down. If I have to force something, that's my first clue that something is messed up, and is about to only get worse.
I'm also not a brass sorter. I do go through the brass, especially range pickups, & toss A-merc & any brass headstamp that I can not ID. Any known brand, WW, RP, FC, Speer, S&B, Geco, PMC, all will load fine w/ jacketed or lead bullets. Some of the foreign brass primer pockets may be on the tight side, but they still work.
I used to sort 9mm by brand. I don't any more and see little difference in the loading or shooting.