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It may be overkill, but I've been trimming and deburring all my brass. It's all mixed and different brands from picking up at the range.
Anyway, I observed that of all the different brands, the Lake City (LC) takes the most trimming. The one that takes the least, as far as this experience goes, is what I think is Russian .223. It has a headstamp that looks like "nny". All the other brass, Remington, Winchester or whatever, was somewhere in between, Just curious - is there a reason for that? Are the pressures different, the brass different or just coincidence?

IIRC, I've seen the nny headstamp on the monarch ammo sold at academy.

.45 rounds I've loaded with the "nny" headstamp have done fine.

ETA: Is that case trimming thing something we're supposed to be doing? 'Cause I've been skipping that part.

For rifle cases yes - for pistol cases, not usually.

Bottle-neck rifle cases stretch a little when fired. Auto pistol cases sometimes actually get shorter. According to the Speer manual it is a consequence of the firing pin strike, since the case headspaces on the case mouth.

For pistol, don't worry about trimming.

edited for punctuation. I need to learn to spell / write, or quit posting.

I meant to emphasize that this was about .223/5.56 cases.

I guess what I'm saying is that the "nny" stuff stretches less and it's pretty cheap, the Lake City stretches most - it's cheap, too. The more expensive stuff stretches a moderate amount.

If I want to do less case prep, I think I would prefer the "nny" (or 'Monarch' brand from Academy, which I think is Russian or some other Eastern Bloc). But does anyone think it performs any different?

I have a case trimmer but haven't trimmed my .223 and got a stuck case in my AR-15 yesterday i think i will start trimming cases cause it put the gun away til i got home,as far as pistol i was told by a guy that reloaded a lot you will wear out the case before it needs trimmed

george wrote:
Rifles (with the exception of some lever-actions), are usually not crimped.

Not sure I entirely agree with that statement. Many rifles will seat the bullet further into the case during recoil, which can lead to problems with pressure.

This can be especially prevalent in magazine fed weapons, and of course the sharper the recoil, the more the possibility exists.

Load up the weapon and fire several rounds. Then take out the remaining rounds and measure the overall length. If it’s changed, then you need to crimp. If it doesn’t change, then that combination of primer, powder, bullet, shell, rifle, temp, and atmospheric conditions are fine. But change any of the variables and bullet movement could happen since chamber pressure could change and impact recoil.

My suggestion is play it safe…trim all rifle cases to the same size and crimp. If they’re trimmed to the same size, then the crimp die will give an accurate and repeatable crimp, and you won’t have to worry about bullet creep while shooting. Another benefit is repeatable pressures, which helps with accuracy.

as to the military rifle cases (e.g. L.C.)....

iirc, according to Speer #13, military brass has thicker walls. since the outside dimensions are standard for the caliber, that makes the inside volume less. powder charge should be reduced (Speer suggests 10%) to avoid dangerous overpressure.

so.. for rifle cartridges, unless you are both (1) working at the very low end of the recommended powder charge range, and (2) not particularly interested in accuracy.. you might consider separating out military cases.

indeed, for rifle many folks treat each headstamp separately.

for pistol, particularly low pressure calibers like 45colt, 45acp, 38spl, most folks throw them all in the same bag.