My Lyman 49th manual calls the trim to length of 9mm Luger at .751" but many of my once fired Winchester and Blazer cases are measuring in at .743" and up. The manual says "The cartridge headspaces from the mouth and therefor case trimming must be uniform and accurate. Do not reduce cases below the trim to length." Are there any inherent issues with the shorter cases? I am new to pistol reloading and trying to learn.
Thanks

Mals

I've been picking up 9mm range brass for upwards of 30 years, never once bothered to trim any of it , loaded 10's of thousands of rounds of it, all with range or my own once fired brass with nary a problem. I'm sure many people will tell you I probably should've, but at this point if any issues haven't occurred, I'm not about to start. In my experience, straight walled pistol cases don't tend to grow like bottle necked cases do.

An overly short case will end up headspacing on the extractor hook and not the chamber. That will tend to hold the case slightly cockeyed and MIGHT contribute to decreased accuracy. That being said I once put a whole box of .380 thru a 9mm just to check. I had to manually cycle the slide as the .380 did not have enough oomph to do it, but the bullet came out the end of the bore every time and accuracy wasn't unreasonably poor. Also if the case is way too short the bullet maybe won't grab properly and can come out when the slide slams the round home. That can be a bad thing. All that being said I don't remember the last time I trimmed a 9mm case to length, at least since I was making my own Makarov brass.

Having loaded 100,000 plus 9mm for pistol,smg,revolver and rifle use I have never trimmed one.Some of the cases I have loaded upwards of 50x. Have never trimmed a pistol/revolver case.

Headspace is on the case mouth, but often the the case is held in place by the extractor. Its only an issue if the cases get too long, & that never happens.

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NRA Cert. Inst. IDPA CSO

To specifically answer the length question, the SAAMI max. length is .754". The minimum length is .744" (-.010") The typical trim length is in the middle, .749" (-.005"). Don't worry about .743" cases.

The headspacing issue has already been stated. Now go reload.

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Waiting for the break of day

Thank you very much for the replies. I am sure I am overthinking this.

Mals

Mals9
Are you measuring case lengths after resizing?

Cases should be measured after resizing.

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I'd like to agree with you BUT

I've loaded 100,001 plus straight walled pistol cases and never trimmed them. Sorry, I just had to one up you!

It's normal to overthink and have extremely high quality standards when you're new to reloading. It's a good habit to be in awareness mode and research each cartridge before reloading. After your comfortable, you get to know what is considered acceptable and what is not, both in your own quality standards and those that the books preach. Like many of us, you should document each load and find your favorites. Then it's less research time the next time you load a particular caliber. I'm up to 9 calibers that I reload for now (After 1 year of reloading) and each it thoroughly documented as to what was the best (OAL, Powder charge, Primer type, bullet type etc)
It sure is a fun hobby using science!

I have never trimmed a 9mm or 45 acp case in over 30+ years of loading. I have trimmed some 38 Special back when I was loading for my Mod 52 for match accuracy, but it was just for a few special matches. My rifle brass gets measured and trimmed.

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H Richard
SWCA1967 SWHF244

If they fired in your gun one time there's no reason not to reload them and shoot them again. Saves the trouble of trimming. I don't believe that I have trimmed any pistol brass.

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"He was kinda funny lookin'"

Nor have I although I did return some new Winchester brass in 7mm STW that had very short necks that were cut off at an angle. As rwsmith indicated, if the brass shot properly once, it should do so again.

Ed

In 9 mm Luger the short answer is NO.
Only trim 9mm if they reach 0.754' , then you can trim them back to 0.749' or 0.750' . It's not that critical.
For some reason the 0.743' cases reload and shoot just fine.

Let me pass on a hint I learned , don't bother measuring and trimming 9 mm or 45 acp , just sweep them up and reload them, all the measuring, sorting by length and head stamp really does no good for ammo shot informally at under 25 yards...unless you're shooting for money.
The targets I have shot at 25 yards do not show any better accuracy between trimmed and sorted cases and mixed cases untrimmed ....exact same bullet and powder charge....I would have never believed it , I would have bet money that sorted and trimmed cases were more accurate.....they are not.
Or at best they might be marginally more accurate....but not enough to go through all that trouble.
Anyone else conduct a test like this. Rifle ammo is another story.
Gary

I did. I trimmed 100 .40 S&W cases for consistency and cleaned the primer pockets and compared them against 100 random length with uncleaned primer pockets. I shot 50 each at 25 and 50 yards from my P226 from a rest. I did not detect a noticeable difference.

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Trucks and guns.

I've not trimmed, though I have sorted.

If you're not shooting a formal precision competition like bullseye, it is genuinely not worth the effort. Case length will commonly be all over the map. 9mm probably more so than many others.

It is reloading law that you must have a special log for keeping track of all of the things that you overthink, overreact, overlook, etc... The log must also document all of the stupid mistakes you make along the way. So, years from now you can read through the log and laugh at yourself.

I have and what I determined was that I am not accurate enough to tell a difference in sorted or unsorted cases in a handgun. I still think all ( rifle & pistol ) cases should be sorted by brand and
I load each box of cases as a unit so every case in the box has an equal number of loadings. That's the way Elmer did it ,that's the way my grandfather did it , and that's the way I still do it.

Rifle cases I can tell a noticeable difference in . I shoot a lot of 7.62x54R in Finnish Nagants and have a pet load that I worked up in S & B cases because that was the only cases that I had available at the time that were reloadable. I later purchased a large lot of Privi brass from Graf & Son and found that the same extremely accurate load did not work in these Privi cases . There was a noticeable difference in case volume between the two brands. I never mix rifle cases and would be very hesitant to mix pistol cases if working up anything like a max load.

Just my 2 cents, your mileage may vary.

Eddie
P.S. As of yesterday Graf had 135 gr Gold Dot SB's in stock .

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Grumpy Old Man With a Gun

I assume this is always the case & in my class I reinforce the importance of good records for your handloads. Nothing worse than having a good load or bad load & then not having the data for it.

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NRA Cert. Inst. IDPA CSO

Unless you can handhold sub 2" groups at 25yds, sorting brass won't be a detectable variable IMO. Even then, most would be hard pressed to determine an accuracy advantage. If yo ucan do 2" or better, then you might just be able to tell sorted once fired from range pickups, maybe.

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NRA Cert. Inst. IDPA CSO

I read somewhere that rifle brass tends to stretch upon firing and resizing, so much that it can thin and have a case head separation after many cycles.

Pistol brass doesn't usually lengthen on firing and sizing, if anything, it shortens somewhat. And, pistol brass rarely needs trimming.

Read this more than 30 years ago, source long forgotten. But I have yet seen any evidence to disprove it.

SAAMI lists the case length for 9mm Parabellum as 0.754 in max with an allowable 0.010 undertolerance. IOW proper cases must be from 0.744 in. to 0.754 in.

SAAMI specifies chamber dimensions from 0.754 in. to 0.776 in. Lo and behold unless your brass is at or over maximum and your chamber is minimum the round will chamber and headspace. What is going on? The obvious answer is that the cartridge is either flopping around or being held in position by the extractor hook. In either case it goes bang and is not really "headspacing on the case mouth" but being driven into either the extractor hook or the case mouth by the firing pin. That's why everybody can "get away with" not trimming and the rounds shoot just fine. No less an authority than Charles Petty penned a piece in Handloader a few years ago about this subject. Somebody was looking out for us a century ago when they designed the 9mm dimensions.

One of the cautions always made is to fire only the correct ammunition for your gun. HOWEVER, I have fired a lot of the much shorter 9mm ammunition in several different .38 Super pistols without incident. The extractor hook keeps the case more or less against the breech face where the firing pin can strike the primer. In addition, the .38 Super magazines have always worked OK with 9mm ammunition. I do not recommend doing this, but it works.

Allowances are such that even some slop is acceptable for most guns to function.

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"He was kinda funny lookin'"

I've never found any 9 MM cases I've checked to have grown enough after repeated reloading that required me to trim them because it exceeded max OAL. If anything, it might shrink a little. But, I have found that both 357 and 44 mag, when loaded with high power loads, will grow enough to require a trim after several loadings. So yes, I have trimmed pistol cases, but only straight wall, rimmed, high pressure cases such as 357 Mag and Max and 44 Mag. And every once in a while I will trim them if I'm starting to get significant variance in a lot of cases on OAL just so I have a more uniform roll crimp on them. Variations in OAL length definitely comes into play with roll crimped cases.

Do you put a taper crimp on 9mm, and doesn't the case length determine how to set the die to crimp? Thanks

Correct, taper crimp on a 9mm.

You setup the crimp die so you get the optimal crimp for the average case length. The more your case lengths vary the lighter or harder their crimp will be. If you have a die that easliy adjusts (Lee FCD) then you can make the changes on the fly. Just another good reason for having a (4) die set.

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Waiting for the break of day