Crimp or no crimp on 9mm?

trimantrekokc · Jun 17, 2014

I have heard different things, some say crimp some say no need? shooting mostly 124gr xtreme with CFE pistol powder and getting ready to load some 147gr w/same powder. if crimping is needed then why do no stores around OKC carry the factory crimp?

help
Bret

TerryKendell · Jun 17, 2014

Reloading Steps For Pistol(You may be new to reloading)
1) Resize & De-Prime
2) Prime & Bell Case Mouth
3) Put Powder in Case
4) Seat Bullet
5) Crimp Bullet (Taper for Rimless cases 9 MM & 45 ACP & others, Roll Crimp for rimmed case 45 Colt Etc.

Some brand of dies combine Step 4 & 5 and 2 & 3

The Lee Factory Crimp Die (I think that is what you are talking about) is used for Step 5

Tell us what brand and model of press and brand of dies you are using for additional help.

drmitchgibson · Jun 17, 2014

I crimp everything.

mike cyrwus · Jun 17, 2014

I dont crimp straightwalled semi-auto cartridges, I de-bell them. if you are crimping semiauto pistol brass past what is considered properly sized, youre wrong

technetium-99m · Jun 17, 2014

it's a little bit harder to tell on 9mm but here's how you crimp a semi auto pistol cartridge.

Seat a bullet and measure the case with your calipers below the bell you still have but high enough you are basically measuring case thickness plus bullet diameter. Set your crimp die to make the mouth the same as this measurement. Tension with the case holds the bullet, not the crimp.

Don't over expand the brass either, doing that can give you interesting bullet setback issues with 9mm depending on what die you use to do the belling.

shootingbuff · Jul 7, 2014

trimantrekokc said:
I have heard different things, some say crimp some say no need? shooting mostly 124gr xtreme with CFE pistol powder and getting ready to load some 147gr w/same powder. if crimping is needed then why do no stores around OKC carry the factory crimp?

help
Bret

Basics; bullets have set back and jump. You need a tight fit/crimp to keep this from happening. Now all but bottle neck semi-auto cartridges take a taper crimp versus a roll crimp. Slow powders usually require a heavier crimp (usually in hvy loads) To keep the bullet from setting deeper into the case when chambering a round you need a tight fit/crimp. To keep the bullet from jumping forward under recoil you need a tight fit/crimp.

How tight? Depends on load and bullet and type of action etc. "I", turn the crimp die down until it is contacting the bullet, then 1/4th of a turn more. You can use your calibers to measure the very leading edge of the brass (works best with same brass) I first check to see if the crimp looks excessive. If not I do the thumb test. Some do this on the scale, but my thumb is calibrated close enough. If the bullet went into the case(use calibers before and after the thumb test) I turn the crimp die in/down 1/8th of a turn until it doesn't seat deeper into the case during the thumb test. Then I load/chamber it five times and measure after the fifth time. If it did not seat deeper then I call it a day. The 9x19 is a tapered cartridge taking a taper crimp. I do bell the brass to ease the start of the bullet seating process. With cast it is even more important. With a beveled base bullet it takes less. A bit more on a progressive to keep speed up. You only want to bell enough to get the bullet to "start" to seat.

The only time a crimp is not needed is when loading a single shot with a tight friction fit that still allows for a complete burn.

YMMV as your reloading habits. I just committed on the basics.

shootingbuff · Jul 8, 2014

BTW you do not need the "factory crimp" If you have a full set of dies they should crimp for you.

Robaire Pullicar · Jul 8, 2014

Yes I use Lee dies on a dillion 650 for 9mm so bullet seating and debelling are done in same stage. I don't use the factory crimp die.

mcintireb · Sep 10, 2014

I load the Xtreme 147 grains. Especially since it is a plated bullet, like shootingbuff said a little belling to start the bullet and a light crimp to hold the bullet. Too much crimp and it could strip the plating on the bullet as it leaves the case. I use Dillon dies and crimp to 0.375 at the mouth.

desert_gypsy · Sep 10, 2014

I do what Mike says and crimp/debell until all my ammo just fits in a case gauge. My dillon sizing die runs the case down pretty narrow so there's sufficient bullet tension below the crimp to keep a 9mm in place.

martinga111 · Jan 4, 2015

If you read RIchard Lee's reloading manual, he says to crimp all pistol cartridges, It's not just for jump and set back reasons, you need to retain the bullets in the cartridge for sufficient time to allow the powder burn to develop the proper shot start pressure. I use a separate factory crimp die, because I use plated bullets with no crimp grove. Mr. Lee states that the bullet seating/crimp combo dies will only properly crimp lead or crimp grooved bullets. In addition such combo dies are hard to set to get consistent results and you can buckle the cases in the set up. For me, I can achieve greater consistency on COL with a separate crimp operation, than trying to do it with a bullet seating die, but's that's just me, I also use a bulge buster to straighten out that last bit of case wall that the sizer die misses. It may be superfluous, but after starting this practice, I have yet to fail a case gauging.