TRIMMING 9MM BRASS???

[BJung]

Maybe you are an accuracy nut that wants to experiment to discover if the case length makes a difference. Using the same headstamp, maybe assemble three lots of 10 of the two sizes and one mix of the two and see what your carefully shot groups print from a rest.

 

[FROGO207]

I, like most here do not trim pistol brass of any caliber. I do however trim all my revolver brass so that I can get a consistant roll crimp. I doubt if most could shoot the difference of trimmed vs untrimmed brass.
More important is to look for those brass cases that have an internal step. Those have less internal case volume and should not be loaded to standard case specifications due to increased pressure when fired. I also reject copper plated steel cases because of different neck tension and possible pressure increases.

 

[rfwobbly]

It is std practice to trim "bottleneck" rifle cartridge cases because they "grow" longer due to the action of the full-length "sizing" process.

However, "straight wall" auto pistol cartridge cases seem to "grow" shorter over time. So that adding a trimming operation to these only results in a shorter case life.

All modern auto pistol cartridges "head space" on the case mouth. That is, there is a squared off step which stops the forward movement of the case as it loads into the chamber. There is no way a case is going to get pinched closed with this type setup simply because this portion of the chamber is not tapered..

 

[9mmepiphany]

I'll be mighty impressed by anyone who can shoot the difference between trimmed & squared 9MM cases vs non.

Maybe some Bullseye shooters, but I am not encumbered by such skills. I'm a good, but not great, pistol shooter.

That's pretty much where I am too. I'm not shooting slow enough or trying for small enough groups to be able to tell the difference

I have proven to myself that a good batch of same headstamp 9MM brass can outshoot a horrid mix of range brass,

even in my hands, and I had so much of it I did just that.

Nothing scientific, but it shoots a little tighter up close and gives fewer "hmm" misses at distance.

I've also proven this to myself.

It isn't about being able to consistently make hits at 50 yards either, but I can tell the difference at targets as close as 10 yards

 

[9mmepiphany]

I set my flaring die up so I can't get a bullet to start at below .740" and just pitch the short ones.

I'm going to have to start doing this...although with the current price of primers, I'll likely set them aside to recover the primers first

 

[bullseye308]

I normally shoot 16k of 9mm a year and I did buy a trimmer 30+ years ago but quickly found it wasn’t necessary and haven’t measured another case length since. I also don’t measure my 357 or 38 cases but I definitely do for rifle.

 

[hms365]

Yes, I will have to be the outlier but have do trim 9mm brass quite a bit. I trim it down 1mm into 9mm Mak.

 

[AJC1]

I can see that being a small difference, but with a taper crimp like we use on 9mm I don’t see it being significant.

That's easily confirmed by observing what guys do for 9mm major. If there was a big difference and important, they would do it. Otherwise it's just unsubstantiated opinion.

 

[Atavar]

That's easily confirmed by observing what guys do for 9mm major. If there was a big difference and important, they would do it. Otherwise it's just unsubstantiated opinion.

So what do the 9mm major guys do?

 

[AJC1]

So what do the 9mm major guys do?

Don't know, I don't do 9mm... when in Rome

 

[JohnMc]

Yes, I will have to be the outlier but have do trim 9mm brass quite a bit. I trim it down 1mm into 9mm Mak.

You're not alone in that.

 

[lordpaxman]

I rollsize, measure, trim, chamfer, uniform the primer pocket, anneal, wet tumble, dry tumble, ultrasonic, and hand polish every single 9mm case I’ve ever shot.

 

[CQB45ACP]

I rollsize, measure, trim, chamfer, uniform the primer pocket, anneal, wet tumble, dry tumble, ultrasonic, and hand polish every single 9mm case I’ve ever shot.

My hero!

 

[lordpaxman]

Gotta love the date!

 

[mstreddy]

I rollsize, measure, trim, chamfer, uniform the primer pocket, anneal, wet tumble, dry tumble, ultrasonic, and hand polish every single 9mm case I’ve ever shot.

What, you don't sort out the cases by weight to with .001 grain differences? --- Rookie!

 

[Atavar]

What, you don't sort out the cases by weight to with .001 grain differences? --- Rookie!

I prefer to fill them with alcohol (lower surface tension than water so a smaller meniscus) then weigh the alcohol and sort by that.

 

[entropy]

If you weigh the alcohol beforehand, you have a tiny shot glass......

 

[Atavar]

I suppose you could fill them with salt then count the grains for more accuracy.

 

[CQB45ACP]

I prefer to fill them with alcohol (lower surface tension than water so a smaller meniscus) then weigh the alcohol and sort by that.

Does alcohol evaporate too quickly to be used alone? I just add 10% to H2O.

 

[tightgroup tiger]

I'm going to have to start doing this...although with the current price of primers, I'll likely set them aside to recover the primers first

I definitely recover my primers before pitching them.

 

[Carl N. Brown]

So trimming 9mm Luger is not a thing among most 9mm Luger cartridge handloaders?
And most cases leave the factory somewhat short of maximum case length specification?

Very interesting. And enlightening.

I briefly owned a 9mm pistol and put a very few boxes of factory ammo through it. I have encountered a factory 9mm cartridge with brass that was too long to chamber in the pistol. Somehow that casing left the factory untrimmed.

So I would recommend plunk testing new unused 9mm Luger casings before handloading first time.

Food for thought:
The 9mm Luger casing is derived from the 7.65 Luger casing which was derived from the 7,63 Mauser casing. The case head and body is tapered, not straight walled, and I suspect the casing headspaces on the cartridge matching the taper of the chamber and not from the mouth of the case touching the front of the chamber.

 

[ballman6711]

And most cases leave the factory somewhat short of maximum case length specification?

I haven't measured any 9mm, but I have (out of curiosity) measured 38spcl, 357mag, 45Colt, 45acp, and 480Ruger. Very few of the cases I measured were at max length, most were closer to min length, and some were below spec. All the cases I measured were new Starline, but I would think any manufacture would be about the same.

chris

 

[CQB45ACP]

I haven't measured any 9mm, but I have (out of curiosity) measured 38spcl, 357mag, 45Colt, 45acp, and 480Ruger. Very few of the cases I measured were at max length, most were closer to min length, and some were below spec. All the cases I measured were new Starline, but I would think any manufacture would be about the same.

chris

I agree...Even mfrs don't produce consistent lengths and are apparently fine with it--Starline advertises their 9mm as being between .748" and .754"