9mm case lengths highly variable?

Just learning to reload. Starting with 9mm Luger casings fired in my P226, and for reuse in same weapon.

Lyman 49th ed. says to trim to 0.754, Lee's 2nd edition Modern Reloading also gives same figure.

When I put a dial caliper to my brass, they range from 0.753 to 0.742 in case length. The average length over about 200 casings is in the 0.745 area.

If I understand correctly, my Lee case trimmer will not remove anything from these casings.

If I were to assemble cartridges with these casings I believe there would be excess headspace which I've read should be avoided. Am I wrong? Why did the fire OK previously?

Newcomer kind of confused here.

No, your good, I have NEVER trimmed a pistol case, revolver/rifle yes. As a matter of fact it's not unusual to open a bag of new rifle brass and most cases be under Spec by a few thousands.!!
Pistol brass gets picked up, tumbled,reloaded without ever seeing a set of calipers. I don't know anyone who does either.

I should add headspace isn't an issue with straight walled cases as found in pistols

warpig1976:

Thanks for your response. Being a new reloader, this is my very first batch, and the books all warn to heed the directions lest a gun explode in your hands. So I'm keyed to being ultra cautious.

If the reality is that cartridges will be somewhat different, and still safe to shoot I can proceed with my climb up the reloader learning curve. Still this batch will only be 10 rounds in size. I'm feeling my way slowly.

Kind regards. Ray

After a while you'll be a pro and know what to careful about and what the corporate lawyers had put into the manuals. Wait until you start reloading rifle rounds and your COAL's vary by 10 thousands!!! that's a real mind bender until you realize why and there's nothing you can do, well you can but in milsurps its mute. Take your time and enjoy yourself, the fellas here are very knowledgeable and are always willing to help.

Are you measuring 1X fired brass or 1X fired & resized brass? Resizing will lengthen them and this is the length you want to pay attention to

A long time ago, I bought a bunch of 30 carbine brass and found they were all "too short", only to realize I was measuring them at the wrong point in the reloading cycle - duh

If 30 carbine is considered a "straight walled pistol case" (I've seen it stated as such on the internet), then the above advice to ignore case length is wrong (i.e. dangerous). Just starting out, measure every thing, be AN.., then learn from your own experience where you can take shortcuts. Never rely on the experience of others to short circuit The Process.

Warpig was specific about rifle cases and a .30 carbine is a rifle. And before one starts the argument about .30 carbine "MAYBE" being a pistol case. I've shot Remington fireball and Thompson Contender in .308 and 45-70. They're rifle too. Reloading manuals put things all over in their books.

His advise on not bothering with too much case prep for pistol is sound. Use them until they crack and salvage them out. You'll probably lose them before that even happens...

9mm Para (Luger) seals at the rim of the case and thus needs to be the correct length. If the case is too short, gas escapes which you´ll be able to see by the burn marks on the outside of the case neck. Fired cases are usually too short, but revert to the correct length (19.0mm) after sizing. So if you measure cases BEFORE sizing, they´ll normally be too short. Luger, who designed the 9 Para, realised that that there was a problem in that the cases had to have a concentric rim and be the correct length to seal adequately. He propounded a stepped chamber which some weapons manufacturers still use. The "step" leaves a distinct mark, similar to a "bottle neck" on spent cases.

Regarding cartridge cases, the main thing to avoid is "too long"! Can lead to rather more serious problems than too short. For those types that take a crimp (not 9x19) a uniform length is useful. Otherwise, it doesn't make a big difference. (Think .38 Spl in a .357 Mag chamber.)

CC, the fact of the matter is nothing I stated is unusual or unsafe. Of course over time Viejorifle will gather information from different sources and come to the same conclusion, he just heard it here first.
As far as .30 carbine being a straight walled pistol case.....Don't believe everything you read on the Internet...;)

I've been reloading 9mm for almost 40 years. During that time I have never ever had to trim a 9mm case what so ever and some of them have been fired over 20 times. Any normal pistol round do not need to be trimmed. The operating pressures involved are too small. The 30 carbine is and always has been a rifle case and has a much higher operating pressure then most pistol rounds. They do stretch and quite a bit so they do have to be checked each time they are loaded.

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.

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.

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.

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.

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?

Quote:

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Originally Posted by 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.

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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.

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.

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

Quote:

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Originally Posted by CrossedCannons

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

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Their original design.

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.