Newbie question... Do I need to trim pistol brass?

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While I don't, some do. There is a size length max like any case but most cases split in the neck (especially if roll crimped) before it stretches enough to trim...

HOWEVER, if you want to crimp using the seating die and the cases aren't the same length, the crimp won't be the same from round to round. Some of us use the Lee FCD to get around this. Does this stop people from seating/crimping in the same die with different length cases? No... most just don't care enough or notice enough of a difference. Again, it all depends how anal you are and how much you care about accuracy.

For me, shooting pistols are just the foreplay before shooting rifle. I don't care much for pistols. I run maybe 100 rnds/weekend just to make sure I can still hit the target. Then move on to hours of rifle work.

Generally for straight wall auto loading cartridges there is no need to trim, unless you're super anal.
Now, for heavy recoiling stuff...44 Mag, etc...then the only way to have a uniform crimp is to have uniform case length.

Revolver cases,,, yes,, makes for uniform case length/ roll crimp


Pistol cases,,, no,, they all short to start with

Yeah, I have a Lee quick trim for 9mmI bought when I started reloading. I've often wondered why they even sell it. Never used it

Some of the guys who shoot heavy revolvers at steel silhouettes do.   Then again, they are shooting for accuracy at 200 yards.

Very few others do so.  I have never trimmed a piece of pistol brass in 25 years of reloading.

This... plus another 5 years to that. He has more posts though...  

I think that the logic of not trimming pistol brass comes clearer if you compare straight wall pistol cases to bottleneck rifle cases.

Sizing both types of cartridges is necessary to restore the case diameter so that it will chamber correctly the next time, but bottleneck cases are more aggressively worked while sizing because they require that the shoulder be set back to pre-fired condition.
Then when a bottleneck cartridge is fired the next time, the shoulder is pushed forward again to meet the shoulder of the barrel chamber.

It's because of the more aggressive sizing of bottleneck cartridges required by their shoulders stretching forward (which takes the case mouth forward with it)  that they "flow" forward (longer) each time they are sized and have to be trimmed often, but since there is no shoulder on a straighwall pistol case, they aren't worked so much when fired and only require sizing back to their proper chambering diameter.
Pistol cases do stretch over time, but very little, and I have found what others have mentioned that the mouth of a straightwall case will virtually always split and cause it to be tossed away much earlier than case stretching would be an issue.

I mic a few in a batch once in a while, but have never come even close to needing trimming.

For the record, all of my pistol reloading consists of .357, .38 Special, some .44 Mag, and a plethora of 9mm, and I do mean plethora.

.45acp brass will actually become shorter over time.

NO!  That was easy!

Do you NEED to?  No, you don't need to.



Most crimping dies seem to be sensitive to case length - long cases get more crimp than short cases.  If you want perfectly uniform crimps, you need uniform case lengths.  Even my Lee factory crimp die needs uniform lengths to yield uniform crimps (but it's a rifle not pistol die).