a while back about Case length in the 9mm, it had an effect on accuracy.

as they are lost long before they need a second trimming.

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Sincerely,

Hobie

When any cartridge Headspaces on the case mouth it is important, moreso than when it headspaces on the Datum line. but check min max case specs. See where your cases fall within these parameters.

All I can offer is my opinion based on my experience and knowledge and it is worth what you paid for it.

1. Uniform length of cases is never a bad thing.
2. Uniform length of cases does help produce a uniform crimp and bullet pull, which in turn aids accuracy.
3. Most folks don't trim auto-pistol cases.
4. Old time Bulleye shooters often trimmed 45 ACP cases thinking it helped their scores.
5. Segregating 9mm cases into lots by length does help in accuracy. I don't waste time trying to trim the little boogers.

I do trim sixgun cases when I am after extreme accuracy. Plinking loads do not get trimmed. I do trim 45 ACP cases when I am after extreme accuracy, but again plinking loads do not get trimmed.

I've probably loaded 25,000 9mm rounds as it is the caliber that I shoot the most, and I've never trimmed a case. I do segregate the cases by manufacturer. Does not trimming make for inaccurate loads? I don't think so. My standard loads will shoot 5 shot 25 yard groups of 3/4" or less out of my Browning Hi-Power GP Comp, and my Sig 226's will do 1.5" 5 shot groups at 25 yards (not just one Sig 226, but all 3 of mine will do that...), and for that matter, so will my standard Hi-Powers...... My Luger pistols will function reliably with my handloads (sometimes an iffy thing with a luger) and shoot groups that run around 1 inch if I can manage their so so triggers OK.

In my experience, more important is overall loaded length. Too many loading manuals and handloaders keep the overall length of their 9mm rounds on the short side, and I've found that most 9mm handguns shoot better with ammo loaded out to the max. end of overall loaded length.....

Just my experience....

JD

I went through a large quantity of sized 9mm Luger cases. I found that the vast majority of them were shorter than the trim length. There were not enough of them that were longer to do a real accuracy test, so I bought a bunch of 9x21mm cases and cut them down to exactly the length they were supposed to be for the Luger round.

In accuracy tests between the trimmed ones and the random (shorter) ones, the ones trimmed to the exact length they were supposed to be had 25% to 1/3 smaller group sizes.

Unfortunately, I rapidly went through the trimmed ones, losing them in various ways, it was a lot of work and it was expensive, so I don't do that anymore.

. . . many, many years. I'm still reloading and shooting the very same .45 ACP brass I started with. They have been "processed" literally dozens of times, and never -- NEVER -- trimmed. They still function just fine thru my '43 Rem-Rand as well as my Series 70 MKIV, and even a convertible Blackhawk. Seriously. I've never experienced a problem with them.

This is also true of all my straight-wall rimmed revolver brass in several chamberings . . . never trimmed, no problems, although none were expected.

I have, over the years, read all the articles warning of serious failure rates on untrimmed auto-pistol brass, and always awaited the onset of such to consider trimming. Never happened. Not sure what to make of this, but most of my fellow shooters report the same experiences.

Strange situation, this.