Trim or not (pistol brass)?

[lefteye42]

3 reliable manuals say it is important to trim 9mm brass. The older posts show most forum members say no.
Using chamber/headspace gage, I quickly find the 'long" cases & set them aside for trim. 198 out of last 200 cases fall within spec, with a spread of .004. To me, this seems okay for reload.
I will appreciate some wisdom on this... Thanks

 

[nettlle]

I don't trim 9mm or 45acp. How long were the ones that were "too long"?

 

[Elkins45]

Never trimmed an auto pistol case in nearly 40 years of reloading. Never found one too long to chamber.

Revolver brass gets trimmed once so it will crimp uniformly.

 

[lefteye42]

I don't trim 9mm or 45acp. How long were the ones that were "too long"?

Thickness of rim standing above face of chamber gage. Also too tall to pass plunk test.

 

[wrench459]

I've never had to trim 9mm brass.
The funny thing is that the case length got longer after resizing while still being within spec.

 

[243winxb]

9mm Luger

.754" is maximum case length. Maximum chamber is .776" plenty of room for brass to grow longer.

But minimum chamber is .754" same as maximum case length.

Unless you measured your chamber, trim brass when it reaches maximum.

The 9mm head spaces on the case mouth. You dont want to fire a plastic gun with the action not fully closed.

 

[Walkalong]

I have never trimmed any auto brass, taper "crimps" don't much care about exact case lengths and I couldn't shoot the difference if it made one.

I do trim all of my revolver brass unless it is bought new as a batch and the OALs are very close. I still chamfer and deburr it though. My .38 Spl is all range brass of many headstamps and the lengths are all over the place, so I trimmed it all and chamferred/deburred it. Same for .357 Mag.

I like consistent roll crimps and consistent case lengths is the only way to get them.

 

[1KPerDay]

If I had to trim 9mm I don't think I'd reload and shoot 9mm anymore.

 

[Dudedog]

Nope never trim 9mm, never measure 9mm, 10000s of rounds all seemed to work fine..
I use the 9mm brass until
neck splits, primer pockets get to loose, or it gets lost. Every now and then I will run into a few with crummy neck tension but that's rare.
Never had any issue in the 5 different 9mms I own.
Never trim .45 ACP. either.

Bottle neck rifle, yep, needs to be trimmed (or a least checked)

 

[ColtPythonElite]

I don't trim any pistol brass.

 

[jmorris]

I do trim pistol brass but they would be fired from pistols like XP-100’s and Contenders, thus bottleneck rifle rounds, fired from handguns.

I was going to say I have reloaded a “bazillion” 9mm rounds and never trimmed a single case but it would be more like hundreds of thousands, to not be an exaggeration.

 

[fxvr5]

Thickness of rim standing above face of chamber gage. Also too tall to pass plunk test.

That would make them about 0.040 to 0.050" too long.

 

[Arkansas Paul]

Never trimmed a single piece of pistol brass.
Don't see myself starting either.

 

[higgite]

.... How long were the ones that were "too long"?

Thickness of rim standing above face of chamber gage. Also too tall to pass plunk test.

What are their measured lengths from head to mouth?

 

[thomas15]

Life is too short to spend it trimming 9mm brass.

 

[George P]

Have never trimmed ANY pistol brass in any caliber in over 35 years. From 32acp, 32SWL, 9mm, 38, 357, 45, not 1. And I have scrounged more brass than I have ever purchased. All goes bang, every time.

 

[Walkalong]

Thickness of rim standing above face of chamber gage. Also too tall to pass plunk test.

That would most likely be one that's simply too fat to fully enter the gauge.

 

[ArchAngelCD]

I have never needed to trim 9mm or any semi- auto handgun brass. It seems they actually shrink slightly with use.

 

[higgite]

That would most likely be one that's simply too fat to fully enter the gauge.

That's why I asked what the head to mouth lengths of those cases are. GMTA.

lefteye42, will the rims of the offending cases enter the mouth of the gauge when inserted rim first? If they do, then again I ask what are the measured case lengths?

 

[ATLDave]

If you're getting brass that is truly too tall to pass a case gauge and/or plunk properly, then you'll need to trim it - but the bigger question is how/why you're getting that kind of length. I've reloaded tens of thousands of 9mm rounds, mostly with brass picked up off the floor of indoor ranges. Since these ranges are places where I'm shooting indoor USPSA matches, a lot of the brass has been previously loaded who-knows-how-many times. I don't recall ever having a round that, after sizing, wouldn't fit a case gauge due to length.

I've had some that wouldn't fit because of width, and more because of a ding in the rim. I don't think I've ever had one "grow" too long to fit the gauge. I think you ought to figure out where this is coming from. Are these new brass? Or resized from your own gun?

 

[ATLDave]

lefteye42, will the rims of the offending cases enter the mouth of the gauge when inserted rim first? If they do, then again I ask what are the measured case lengths?

Will that work with a tapered 9mm case? 9x19 is not a true straight-walled cartridge...

 

[Toprudder]

I would measure with calipers and not depend on the case gauge. It has been my observation that if a case doesn't fit the case gauge, it is because of some other defect than case length, most often it is because of a burr on the rim from an extractor. Turn the case around and see if it starts to enter the case gauge (it won't go all the way, because as @ATLDave pointed out, 9mm is a tapered case) the rim should actually go down into the gauge for a short distance.

 

[entropy]

9mm would be the last brass worth trimming simply because it is very available for free. I have tons of it, and I don't even own a 9mm currently, just from range pickups. (I eventually will have a 9mm again, so I'm building up a supply of cases.....)

 

[ATLDave]

9mm would be the last brass worth trimming simply because it is very available for free. I have tons of it, and I don't even own a 9mm currently, just from range pickups. (I eventually will have a 9mm again, so I'm building up a supply of cases.....)

Yeah, the level of effort I would be willing to expend to remediate a 9mm case that has developed some flaw that is not fixed with the usual run through a sizing die is... basically zero. For many of us, the cost of 9mm brass is the cost of bending over.

 

[Toprudder]

I used to take the time to ream/swage pockets on NATO 9mm, but I am to the point now that I just scrap them. I always come back from the range with more 9mm brass than I shot.