To crimp or not to crimp 9mm Major loads?

[Hopper]

Getting back into competition/reloading after a number of years.  The weapon is an Sti DVC Open 9mm.  My Dillon die set-up included a crimping die.  Reloading for 9mm Major.  Is a light crimp a good idea or not.  I am reloading with Winchester AutoComp (starting load 6.4gr-working up from there to probably 7.1 depending on the chronograph results).  The bullet is a 124gr Montana Gold JHP.  Primers are CCI 500.  Any help would be greatly appreciated.

[Garmil]

Just get rid of the bell and prevent setback, no more.

[kneelingatlas]

0.378"

[Wheeljack]

What I found interesting in crimping the 9mm is that the taper crimp should be bullet diameter plus shell thickness.  (This is with a jacketed bullet, a lead bullet may require an added .02 crimp)  A .355 bullet in a shell with wall thickness of .01 x 2 = .02, equals .375 for the crimp at the mouth of the shell.   But, I found that the .355 bullet seated to a selected depth had a  diameter of .353 at the mouth of the shell due to where the ogive started, below the shell mouth.  So, it would appear that you could crimp the shell mouth to .373 without imprinting the bullet.   I noticed this when I looked at the shell mouth around the bullet and found space between the bullet and shell.  Don't you hate it when it gets this technical.

[Hi-Power Jack]

23 hours ago, Hopper said:

  Is a light crimp a good idea?

You don't need a "crimp" on a 9mm - just need to remove the belling

so the cartridge case is "straight"  again - not "crimped" and not belled.    

[Absocold]

I run a very slight roll crimp. Mostly just to make sure there's no rough edges at the top of the brass and to help prevent bullet setback during feeding.

[JFoley001]

On ‎11‎/‎24‎/‎2016 at 9:23 PM, Absocold said:

I run a very slight roll crimp. Mostly just to make sure there's no rough edges at the top of the brass and to help prevent bullet setback during feeding.

School me on this. Obviously a very slight roll crimp wont have any adverse effects, as you can attest. I have been wondering if a heavy roll crimp could interfere with proper headspacing of the crimped brass in a barrel. Thoughts?

[ano]

I load 9 major without a crimp die. 

 

roll crimp?! 

 

how can you even get setback?  9 major with most powders are compressed pretty hefty. bullets falling out is more often an issue

[Hi-Power Jack]

1 hour ago, ano said:

how can you even get setback?  9 major with most powders are compressed pretty hefty. 

Not 7 grains of WAC ...   

[Sarge]

4 hours ago, Hi-Power Jack said:

Not 7 grains of WAC ...   

Not with 8 grains WAC either!

[ano]

since its a numbers game.. 9grs of 3n38.. boooom mike drop  1.22oal. 

funny thing is pressure is so low its within saaami/cip. 

[Absocold]

 Plenty of people don't bother to crimp 9mm but for me, it's a safety thing. It doesn't even require an extra step, it happens during bullet seating. It doesn't matter if the load is compressed or not, compressed loads may help prevent setback but they do not eliminate it.

 

And here's why I do it. Loading a round once? No problem. Loading it twice? Still, usually no problem. How about three times? Four? How many times can the bullet slam into the feed ramp / barrel throat / chamber roof before it sets back? You fire a stage and eject the last unfired round to show clear. That round gets tossed in with the rest of your ammo. It will get loaded into the gun at least a second time. But the law of averages says that eventually a round will get loaded three times, maybe more. A little crimp, one less thing to worry about. You may think it's very unlikely, I think people win the lottery all the time. This is one particular lottery I don't care to play.

[ano]

tapercrimp wont make the bullet hold any better, its just for removing flare from dropper and such. 

 

ROLLcrimp on other hand, yeah that baby is stuck, but we dont rollcrimp 9. 

[Absocold]

On 11/24/2016 at 9:23 PM, Absocold said:

I run a very slight roll crimp. Mostly just to make sure there's no rough edges at the top of the brass and to help prevent bullet setback during feeding.

 

[RiggerJJ]

For what its worth, my understanding is roll crimping is for revolver ammo only, because non-rimmed brass uses the case mouth for headspacing in auto loaders.

Also, do NOT use any style of crimp to avoid setback. Neck tension should be sufficient enough to prevent setback. Taper crimp just enough to remove flairing.

Suggest a U die, I use em on 9mm, 40, and 45... No setback...

jmho

jj

[Sarge]

1 minute ago, RiggerJJ said:

For what its worth, my understanding is roll crimping is for revolver ammo only, because non-rimmed brass uses the case mouth for headspacing in auto loaders.

Also, do NOT use any style of crimp to avoid setback. Neck tension should be sufficient enough to prevent setback. Taper crimp just enough to remove flairing.

Suggest a U die, I use em on 9mm, 40, and 45... No setback...

jmho

jj

Ditto. Crimp is so misunderstood !

[RiggerJJ]

6 minutes ago, RiggerJJ said:

For what its worth, my understanding is roll crimping is for revolver ammo only, because non-rimmed brass uses the case mouth for headspacing in auto loaders.

Also, do NOT use any style of crimp to avoid setback. Neck tension should be sufficient enough to prevent setback. Taper crimp just enough to remove flairing.

Suggest a U die, I use em on 9mm, 40, and 45... No setback...

jmho

jj

Oh yea, i load both major and minor 9mm this way...

[Wheeljack]

On 11/24/2016 at 9:23 PM, Absocold said:

I run a very slight roll crimp. Mostly just to make sure there's no rough edges at the top of the brass and to help prevent bullet setback during feeding.

The "rough edge" is the ridge inside the top of the brass.  If you roll crimp you may scrape the bullet.  Test it with a blank.  Roll crimp the shell then remove the bullet from the shell.  There should be a  ring around the bullet from the inside ridge.  It will scrape plated and coated coatings when fired.

[amada8]

10 hours ago, RiggerJJ said:

For what its worth, my understanding is roll crimping is for revolver ammo only, because non-rimmed brass uses the case mouth for headspacing in auto loaders.

Also, do NOT use any style of crimp to avoid setback. Neck tension should be sufficient enough to prevent setback. Taper crimp just enough to remove flairing.

Suggest a U die, I use em on 9mm, 40, and 45... No setback...

jmho

jj

Thank you RiggerJJ.  I thought it was well established that a taper crimp for 9mm was the norm.  (Enough to remove the belling needed to insert the bullet).  No crimp or (gasp) roll crimp..... I really had a hard time believing this wasn't a troll thread.

[Absocold]

I think y'all are paying too much attention to the evil and dreaded words "roll crimp" and not enough to the "very slight" part. When I eventually move my 9mm reloading over to the 1050 and have more stations to play with, I'll stop the roll crimp and add a factory crimp die. If we were talking about standard loads then I wouldn't sweat a crimp, but the original poster specifically said Open, which almost always means Major. A lot less room for errors.

 

If I was one of those disgustingly wealthy people who can afford to buy brand new brass and only load it once or twice, I wouldn't worry about a crimp. But for this non-millionaire who will load anything I found buried in the dirt for who knows how long, fired who knows how many times, at what power factors and from any manufacturer, a teeny bit of crimp is simple insurance. I can't be arsed to do a press test on every single round I load so a smidge of crimp lets me sleep better at night. Betting my eyes, fingers and gun on what is basically neck tension on junkyard brass gives me the heebie jeebies.

[Hi-Power Jack]

16 hours ago, 57K said:

  I never load shorter than 1.122". More at 1.132" and most at 1.142". 

 

That seems a little short for 9mm Major with 124 gr JHP's.

I never load shorter than 1.145" and load most at 1.165".

[9146gt]

On 11/28/2016 at 5:33 AM, ano said:

since its a numbers game.. 9grs of 3n38.. boooom mike drop  1.22oal. 

funny thing is pressure is so low its within saaami/cip. 

Who did you get to pressure the loads?

 

Tom

[abb1]

I use a slight taper crimp using my factory crimp die. Rounds feed 100%, make major power factor, and are as accurate as can be. Not too sure if it's right or wrong, but it works!

Edited December 16, 2016 by abb1

[carlspeed]

Whats the difference of how powerful the round is? Wouldn't you still need decent crimp to make the whole package work?

[Bkreutz]

2 minutes ago, carlspeed said:

Whats the difference of how powerful the round is? Wouldn't you still need decent crimp to make the whole package work?

The only thing a crimp is supposed to do is to take the bell out of the case that was formed to facilitate bullet insertion. If you crimp to hold the bullet in, you have other problems and the accuracy will suffer.