9mm reloading

[Russman]

Just wondering when reloading 9mm what the minimal case length acceptable would be?My manual states the case should be .754”

[jmort]

That is SAAMI Spec

[Russman]

Yes,so I was just wondering the acceptable minimum case length.

[tazman]

Most semi-auto pistols feed the case up under the extractor from underneath during the feeding cycle. The extractor holds the case against the breechface and the chamber mouth serves as a secondary stop for the cartridge.
With this system, you can use cases of varying length and the pistol will still function as it should. I have even tried using 380 auto cases with the boolit seated out to normal 9mm OAL and they work fine.
For best accuracy, it is more important that cases are all the same length than what that measurement actually is.
Personally, I don't check case length on 9mm cases any more. I am not a good enough shot to make use of any possible increase in accuracy due to absolutely matched cases.
If you need a specific dimension for case length for best accuracy in your pistol, you would need to test a number of different length cases and see which length groups the best.
Each pistol makes it's own rules in this regard.

[Russman]

Thanks tazman.Thanks for the great insight.Just wanted to make sure that a case measuring say.744 wouldn’t put me in any danger due to the pressures being increased with the shorter than normal cases I have since they are.010 smaller.I would naturally go with recommendations for starting loads.

[jrmartin1964]

I don't know what manual you are using, but most that I have will list a "maximum case length" and a "recommended trim length", which is usually anywhere from 0.004" 0.010" shorter than the recommended max. So long as you maintain a consistent O.A.L. on your loaded cartridges, one that will pass the "plunk test" and the equally important "magazine test", the shorter 0.010" in length of your cases will not cause you any problems.

[Russman]

Ok.I use the Lyman.Thanks!

[Petrol & Powder]

I can't remember the last time I even bothered to check the case length of a 9mm casing.

[Wheelguns 1961]

The saami max is .754 The trim length is .749. I usually discard anything shorter than .745, but I am extremely anal.

[mdi]

FWIW; the OAL is from the case head to the bullet tip. When you seat a bullet you are seating to a depth as measured from the case head, so case length won't affect case capacity when a bullet is seated. You can get the same OAL with any case from minimum to maximum case dimensions...

[P Flados]

Some 9mm guns will reliably shoot 380s with the case head spacing on the extractor. Some will fire 380s intermittently, some probably wont fire 380s at all.

The 9mm is intended to head space on the case mouth. If your cases are too short, you are heading in the direction of potential FTFs (depending on your gun).

[gwpercle]

I can't remember the last time I even bothered to check the case length of a 9mm casing.

I remember....Never ! I've never trimmed one either.

[dverna]

I can't remember the last time I even bothered to check the case length of a 9mm casing.

Yep. BTW, never check any pistol cases for length.

[Ed_Shot]

I check the length on my 9MM brass and cull brass longer than .752 and shorter than .748 simply because if I set my Lyman M die (or Lee expansion die or NOE expansion plug) to adequately expand (short) brass which is .742~.740 in length so that no lead is shaved when the boolit is seated, that same expansion die setting will make .754 long brass look like a tuba.

[poppy42]

I remember....Never ! I've never trimmed one either.

Same here and I haven’t use factory ammunition in years. Nothing but my reloads in my 9x19’s and 9x18 Makarov’s

[Mr_Sheesh]

I'd be a bit concerned about shooting 380 ACP in a 9mm weapon -

9mm rim diameter 0.392 in (9.96 mm)
380 auto rim diameter 0.374 in (9.50 mm)

Bit of a difference.

[tazman]

Yet people fire 9mm using a 40S&W slide which has an even larger difference(.030) regularly by using just a different barrel.
9mm ---.394
40S&W ---.424

[GONRA]

GONRA sez - most (all)? of us can pick up Range Brass, Reload and Blast Away Just Fine.
(Clean dirt off, weed out Berdan primed / tiny flash hole Boxer brass FIRST!)
Yer air compressor is yer Friend on his stuff.....

[trapper9260]

I check the length on my 9mm brass and I go with the min. of .744 and anything below that I load a different data I made and shoot them in my 9mm wheel gun that have a moon clip. I get more use out of the brass and I shorten the brass more that way I can pick them out when I tumble them with other brass.

[35remington]

The slop of a 380 case is the problem in a 9mm chamber but low pressure may let you get away with it. And probably will. The area of greatest discrepancy is where the case is thickest.

Shooting a 9mm barrel on a 40 slide using 9mm ammo is not the same thing, because you are using 9mm ammo in a 9mm chamber. The 40 slide offers no difference in case support versus a 9mm slide when in battery. The barrel offers the case support, and there are no slop issues shooting 9mm in 9mm barrels on a 40 slide when the cartridge is fired.