9mm case length, once-fired brass already too short?

[MrSpiffy]

I'm in the planning stages of getting into reloading, and am just waiting for my final components to arrive. I was playing around with my case trimmer today to see how to set it up, when I measured a couple of pieces of 9mm brass. They came in at 0.745" on my caliper.

According to the Lyman 49th edition reloading manual, this is already 0.006" too short, and they specifically state not to trim shorter than their trim-to length of 0.751".

I guess I'm a little confused. This seems to mean the brass was already too short when I fired these rounds. If so, what does that mean for my reloading efforts with this brass? Can I reuse these? Or are they unsafe to fire?

It's possible that my caliper isn't accurate, since it's a dial caliper I got at Harbor Freight. Maybe it's time to upgrade?

ETA: Removed other edits. I checked the base of a couple of cases, and they came out to 0.390", which is close to the case spec. So, the caliper can't be off that badly, at least for shorter measurements. Looks like my cases are, indeed, too short.

So... I guess it's back to my questions. Did the manufacturers have cases that were too short? Or did they shorten during firing? (I understand this can happen with straight-walled cases.) Either way, wouldn't that mean they're unsafe?

 

[243winxb]

May get longer after sizing. .744" is SAAMI minimum.

No trimming till sized brass is longer then .754"

 

[SARuger]

Size first then check to see if it needs trimming. Honestly, with 9mm, I never check it for length.

Just tumble them, then run them by the hundreds, never an issue.

 

[satexas]

I recently received a box of 500 new .41 magnum Starline cases. They too are shorter than listed TRIM TO length. Even after sizing. I'm not going to worry about it. I already loaded 100 keeping to at or just below listed COAL depending on the bullet I used.

 

[Sam1911]

Not a worry.

 

[ReloaderFred]

Don't over think it. Those rounds will load just fine, and handgun brass hardly ever needs trimming.

Hope this helps.

Fred

 

[Elkins45]

I have never trimmed a piece of auto pistol brass in 30 years of reloading. I have yet to see a piece of brass so long that it causes chambering problems, nor so short it causes headspace issues. The extractor usually provides the actual headspace anyway.

Revolver brass gets trimmed so it is uniform, but that's because it is roll crimped. Auto pistol rounds are taper crimped and this is much more forgiving of variations. My advice is to stop measuring it and stop worrying.

 

[rjbmjb]

My Lyman 47th says the same thing, but my Spear Reloading Manual #14 lists .744 as trim-to length, which (as 23winxb noted) is the saami minimum. I checked my brass, and most were .744 - .745. I have loaded thousands of these and never had a problem.

 

[GRIZ22]

I have never trimmed a piece of auto pistol brass in 30 years of reloading. I have yet to see a piece of brass so long that it causes chambering problems, nor so short it causes headspace issues. The extractor usually provides the actual headspace anyway.

Revolver brass gets trimmed so it is uniform, but that's because it is roll crimped. Auto pistol rounds are taper crimped and this is much more forgiving of variations. My advice is to stop measuring it and stop worrying.

I've been reloading over 40 years.

See Elkins45 response. I agree.

 

[Walkalong]

Unless you are trying for extreme accuracy don't worry about it. You could size everything, then sort out all the cases into groups by weight and length, but I know my mixed brass 9MM loads can out shoot me. Even same head stamp will vary some. I have never trimmed a 9MM case. I do trim all revolver cases, or buy new stuff that is consistent in length.

No worries, load it up.

 

[Jim Watson]

You will not have to trim 9mm. As you have found, it runs short to start with and a straight case will more likely shorten with reuse, not stretch. I usually lose it in the gravel and grass before it wears much, anyhow.

I once picked up a few Hornady .45 ACPs that were over length. It must have chambered and fired in somebody's gun but it wouldn't in mine. Only a few, so I discarded them rather than fool with trimming. But that was once since I started handloading in 1970.

 

[kcofohio]

About 4 yrs. ago when I 1st started reloading, from reading certain manuals, I was led to believe that it was a must to trim all your cases. After I had acquired 1000 or so casings with mixed headstamps. I soon discovered the variance or lengths and shortness with some headstamps were like the OP found. It seemed they were S&B, or CBC that were short.

Maybe it was this forum, not sure. But after reading from the old timers , I soon realized it wasn't nessesary for semis.

I did opt for seperating by headstamp for the bell mouthing process. Though that isn't 100% guarantee.

 

[kingmt]

I have seen 9mm brass that had been feed to a 40 S&W. I'm pretty sure it didn't headspace off the mouth of the case.

 

[forrest r]

You ought to measure a handful of range brass some time, it's a real eye opener. Typically 9mm brass (straight walled pistol brass in general) will shrink in length with repeated reloading/re-sizing.

Where the real difference in brass length come into play is the reloading dies you are using and more importantly how those dies are adjusted to crimp the cases. Some mfg's make their dies to use 1/8 turn to crimp the brass others 1/4 turn to 1/2 turn. Dies are made with 7/8-14 threads. That's telling you it takes 14 full turns to move the die up or down one inch. That means that a crimp die that is adjusted 1/8 turn will only crimp cases that are within .009" of where they were set. So if you set your crimp die by putting in a .751" case and then gave it a 1/8 factory recommended turn. You will only be able to crimp cases that are .751" to .742" long. And in actually the "target" length for any crimp die is 1/2 of it's max turn setting. Meaning A .009" adjustment is at it's best with cases in the .751" to .747" range..

The case oal affects the crimp more than anything. Bullet seating is not affected and even though a 9mm case head spaces on the case mouth. A case 20/1000th's less than the recommended .751" isn't going to hurt anything. Trying to crimp a case that's 20/1000th's too short on the other hand makes a huge difference.

 

[ArchAngelCD]

When the die maker tells you 1/8 turn it's a guide, not set in stone. It will not matter if you are slightly off because with pistol cartridges you are not crimping to hold the bullet, only to remove the bell added to aid starting the bullet.

 

[Dudedog]

but I know my mixed brass 9MM loads can out shoot me

Agree
(and Walkalong is a much better shot than I am)
I don't trim 9mm brass, and I don't even measure it.
If it splits or the primer pocket gets loose I toss it, otherwise it is just load, shot, repeat.

 

[forrest r]

When the die maker tells you 1/8 turn it's a guide, not set in stone. It will not matter if you are slightly off because with pistol cartridges you are not crimping to hold the bullet, only to remove the bell added to aid starting the bullet.

1/8 turn isn't written in stone. But if you look at the different mfg's recommendations on how to adjust their crimp dies, you will get an idea of the bevel they are using in them.

Hence one mfg recommends 1/8 turn and another recommends 1/4 to 1/2 turn. That's called a clue. The makers of the die that recommended a 1/8 turn did so for a reason. Namely the angle of the crimp bevel and how far a 7/8-14 tread travels per turn. The other thing they go by is the recommended case oal, With the 9mm it's .751". When you know the case oal, the crimp angle and the amount a 7/8-14 thread will travel you don't have to use a dart board to figure out where to start testing a crimp. It's called doing the math.

There are different camps on what a crimp actually does.
I tend to use the same crimp as factory ammo, namely .003".
I tend to believe my own eyes and others that are considered authorities about reloads when they recommend a #50 push test and why a crimp aids in the failure rate.
I tend to believe that a crimp not only aids in stopping bullet setback, it is extremely important for accuracy from consistent ignition.
I tend to try to load my reloads so they actually look like something I would buy from a gunshop or store. A couple different 9mm (.358" bullet) & 45acps (.452" bullet), both have no bullet bulge (watermelon look) and have a .003" taper crimp.



If reloads look like this you don't have to worry about a crimp. And typically when someone posts pictures like these of their reloads there's always "gotta have good neck tension" somewhere in their post. Coupled with "you only need to remove the bell yada-yada-yada"

 

[ArchAngelCD]

Well, I wasn't trying to yada-yada-yada you and not everything I write is meant directly for the one reader. You may know all about dies but a lurker reading posts to learn might not. I was only trying to point out the number overturns or the thread angle or any other angle you want to obsess over means nothing if you mearly adjust the die to remove the flare. That's why I mentioned the crimp and it's reason for being. I didn't think I needed to explain that deeply but obviously I have to explain everything these days or be accused of acting like a very bad sit-com.

 

[Walkalong]

I never recommend to turn a crimp die "X" amount. For a proper taper crimp on 9MM cases we need to adjust the die so all the belling is removed form the shortest cases which will give us .001 or .002 inward movement on the longest cases. .003 would likely be fine as well, but don't over do it.

No amount of taper crimp can fix poor neck tension. Can a proper (Not over done) taper crimp help bullet setback? Maybe a little, but neck tension is doing 95% plus of the work IMHO.

See Post #13

 

[Sunray]

Relax. The SAAMI spec is .754" -.010". The chances of you ever having to trim 9mm or any pistol cartridge are slim too. They just don't stretch much.

 

[model 649]

Relax. The SAAMI spec is .754" -.010". The chances of you ever having to trim 9mm or any pistol cartridge are slim too. They just don't stretch much.

THIS ^^^^
Over 25 years of loading the 9's, I've never had to trim cases.

 

[MrSpiffy]

Wow! Lots of replies! Thanks, everyone! It's great to know these are just fine to use. I'll just clean up the cases and get to reloading them.

Sorry for not responding sooner, I'm not sure why it didn't notify me of replies.

Happy New Year, everyone!

 

[forrest r]

I never tell anyone to adjust a crimp die x amount either. I'm simply putting out there what the different mfg's that actually are making the dies are telling people to do.

I also understand by how far up and down I move a crimp die will affect a specific height.

I also understand different crimp die mfg's use different angles in their crimp dies. Some are extremely sharp/heavy. Others have a gradual taper to them.

rcbs recommends stating with a 1/8 turn
lee 1/4 to 1/2
lyman 1/2 turn
hornady recommends starting with a 1/8 turn
dillon recommends 1/8 turn
Lyman dies are interesting because they have a lllloooonnnngggg gradual taper to their crimp dies that will affect 20/1000th's difference in the length of the differenence in typical 9mm range brass. Here's what lyman says.
B. Taper Crimping: This operation requires a special Taper Crimp die which is used to reduce case neck diameter by .001" to .002". This increases case mouth tension, improves feeding, and provides proper headspace on rimless cartridges which headspace on the case mouth. With the completed, but uncrimped, cartridge in the shellholder, the bullet seated to proper depth, and the ram in the full “up” position, screw the Taper Crimp Die down until it contacts the case mouth. Lower the press ram and turn down the die about 1/2 turn. Measure the case mouth diameter and continue adjusting the die by turning it down until the taper crimping operation results in a neck diameter .001" to .002" less than obtained in the standard seat/roll-crimp die. When the crimp is satisfactory, secure the die lock ring and its set screw. Caution: A reduction of case mouth diameter greater than .003" may cause bullet deformation and often results in a loose bullet.

The yada-yada-yada was not directed at anyone.

I just didn't feel like getting into the crimp/no crimp and why. If you ain't sure then read the above from lyman because they are sure. That's what they get paid to do.

 

[rfwobbly]

The yada-yada-yada was not directed at anyone.

Nevertheless, I feel violated. I'm going to my safe space, suck my thumb, and cuddle my Hillary lapel button until the feeling subsides. Where's my participation trophy when I need it ?

 

[Walkalong]

I also understand different crimp die mfg's use different angles in their crimp dies. Some are extremely sharp/heavy. Others have a gradual taper to them.

This is true, and Hornady (1/8" turn recommended) is using a very sharp crimp ledge which to me is unsuitable for a "taper" crimp. It seems they are using inserts for double duty which is a mistake IMHO, as it doesn't do either job great. That same insert does a pretty good roll crimp though. I log it as a "Modified" roll crimp in my Excel data log. I won't use it for a taper crimp because the angle is too sharp and the adjustment too critical, especially taking case length differences into account.

"Modified" Roll Crimp done with a Hornady insert in .32 Mag.