9mm case lengths highly variable?

[Johnny Peppers]

As WarPig noted, the case length is not an issue (unless it is too long). In firing an auto pistol the cartridge is stripped out of the magazine, slides up the breech face and under the extractor where it is held. There is no way that you could trim and load all your ammo so that it exactly headspaced on the front of the cartridge case. General Hatcher demonstrated that firing too short brass in a pistol (auto) made no difference. He fired the .380 ACP (9mm Kurz) in the 9mm Luger. As described, the cartridge was held against the breech face and fired normally other than the fact that it didn't have enough power to cycle the action. Pull the toggles back, release them, and another cartridge was loaded ready to fire.

I don't know about 9mm Luger, but .45 ACP shrinks in length with use. Have never trimmed .45 ACP brass either. Just load your cartridge to the proper overall length.

[villiers]

Whoever Gen. Hatcher might have been, his experiment proved conclusively that cases in chambers that seal at the case rim need to be the correct length in order to achieve regularity and effectiveness. The shorter cases will show burnt powder residue from gasses escaping to the rear. The experiment would furthermore show with absolute certainty what is to be expected, that the action does not cycle correctly and the round will almost certainly not achieve the same ballistic properties as with a case with the correct length.

[WarPig1976]

Nobody is saying fireing .380 in a .9mm is a good idea. What the OP is concerned with is his average case length for his .9mm cases .745 which is .009 under trim to length for .9mm. Will he see some blow by? Probably, does it matter? No it does not, Nobody is arguing your point Villiers,,he has already learned too lite of a charge can cause blow by and malfuction,, in the reloading world it simply is not common practice to concern oneself with straight walled pistol case length. What we do worry about is "c.o.a.l" cartridge overall length and charge weight, seating the bullet too deep can cause pressure spikes and blow the firearm up in your hand but that's off subject.
I don't want to confuse the OP, I can remember being in his shoes.

[villiers]

OK WP, I agree with that. Georg Luger (who first designed the 9 Para case) was concerned to achieve max. efficiency and realized that the straight walled case did not seal as well as the previously used bottle-neck 7.65 Para. As 9 Para is often used for competitive shooting, many re-loaders attempt to optimise performance in order to achieve the best possible seal against the step at the end of the chamber. Using spent cases, it is of little use to measure case length before re-sizing. Once re-sized, practically all cases will be within tolerance. Personally, I only reject about 1 - 2% percent of all the cases I collect that are drastically too short.

[browningautorifle]

I've only shot very little Luger...the one I remember was with Remington factory ammo and after, during examination of casings, I noticed a slight shoulder to the fired casing. Is this what you speak of in Luger's design?

[Johnny Peppers]

Whoever Gen. Hatcher might have been, his experiment proved conclusively that cases in chambers that seal at the case rim need to be the correct length in order to achieve regularity and effectiveness. The shorter cases will show burnt powder residue from gasses escaping to the rear. The experiment would furthermore show with absolute certainty what is to be expected, that the action does not cycle correctly and the round will almost certainly not achieve the same ballistic properties as with a case with the correct length.

Gemeral Hatcher was a brilliant ballistician, and spent most of his Army career in small arms research and development.

Julian Hatcher - Wikipedia, the free encyclopedia

Sorry that you didn't understand the reason for firing the .380 ACP in the 9mm Luger. It was merely to demonstrate that excessive headspace on a rimless cartridge in an auto pistol such as the Luger is not a danger. General Hatcher did not recommend that .380 ACP ammo be substituted for the correct cartridge, but that with .072 excessive headspace the .380 ACP cartridge posed no danger.

Headspace on 9mm ammunition to be fired in a revolver is important, as the cartridge position in the cylinder is critical to functioning and firing.

[TDH]

In the immortal words of Buffalo Springfield, For What It's Worth, and this is only my 2 cents of course in my experience I have never trimmed a pistol cartridge. As said earlier they will probably fail long before they ever become long enough to trim. Rifle brass on the other hand does grow when resized. It also gets thinner as each time you resize it as it stretches. That being said let us return to the .30 carbine. It is a rifle cartridge and it is not a straight walled cartridge. It does have a slight taper and you can feel it the first time you resize it. .30 carbine must be trimmed to the proper size or it will not chamber.
I have never had a problem with 9mm cases being to short. I have had a problem with them being to light to cycle some pistols like the P38. What cycles in your Kahr or Taurus or other 9mm may not be stout enough to cycle the Luger or P38. That comes from experience.

[CrossedCannons]

OK, I'm more than just a bit curious now. What distinguishes a "rifle" cartridge from a "pistol" cartridge?

[browningautorifle]

What distinguishes a "rifle" cartridge from a "pistol" cartridge?

Their original design.

[Gun Surfer]

Been reloading 9mm for 30+ years. Never trimmed a case. They just don't grow much if at all. I do not ever have any significant signs of gas leakage round the mouth. Regardless, they all go bang, hit very hard and accurately at 25yd. That's what matters.

I dont use a case gage either. So in years of shooting Glocks with reloads, I cannot remember a failure to feed, eject or fire. That doesnt mean I didnt have any, but if I did it was so seldom that I don't remember.

For self defense I have high quality factory ammo.