9mm crimping

[Field]

so basically i hear there isnt much need to do any crimping per se with 9mm cartridges you more need to just flare the case mouth enough with the expander die to allow you to lightly set the bullet on top of the case before seating? is this right?

most of my loading i have been seating to around 1.125 col maybe you need to do crimping if it is being seated shallower to 1.15 col or higher?

[slowr1der]

I wonder about this too because the Hornady reloading manual I have says to apply a light to no crimp for the 9mm cartridge. Yet I thought you wanted to crimp for semi auto's?

[Brian Pfleuger]

You need to crimp for semi-auto rifles (particularly bottle-neck cartridges) because there is not a lot of surface in the case holding the bullet in place. For most straight walled semi-auto handgun cartridges, the only "crimp" necessary is to remove the modest flare produced to seat the bullet.

There's an easy way to tell if you need to crimp. If you have factory ammo, measure one of your reloads and load it in a magazine under a factory load. After firing the factory load, extract and measure the hand loaded round. If the round shows set-back from the chambering process then you need to apply a little crimp. Obviously, one round isn't the whole story. You may want to try this a number of times. You can also repeatedly chamber and extract a round (remember the rules of gun safety!) and see if that produces any set-back. Manually chambering is not as good as firing conditions though.

[FrankenMauser]

You need to crimp for semi-auto rifles (particularly bottle-neck cartridges) because there is not a lot of surface in the case holding the bullet in place. For most straight walled semi-auto handgun cartridges, the only "crimp" necessary is to remove the modest flare produced to seat the bullet.

What he said. ^

I don't crimp for tension. I crimp to remove any flaring that didn't disappear with bullet seating. So, it's really just a "de-flaring" step, with a crimping die.

[vladan]

9mm luger is tapered cartridge so it has less tension than straight walled cartridge and each brass is different (that is the reason I sort brass by the headstamp) and some like winchester dont require crimp while some do need crimp. I determine the amount of crimp by the "thumb test" - measure COL of finished round, stand it on the bullet and press with your thumb ( 10-15 LBS of force ). then measure COL again, if you don't have a setbact ( or minimal .001-.002) you are good to go, otherwise a little more crimp is needed.
Just don't put too much of crimp, that might result in exactly opposite effect ( even more setback) and headspace problems...

Another test you can do with your gun ( just be sure to take the firing pin out before you do this ) is to measure your finished round, load it in the magazine and release slide of your gun to load the round in the chamber. eject the round, and measure the COL again to see if there is any setback.

[MR 8x57js]

The test i do with your gun is to measure your finished round, load it in the magazine and release slide of your gun to load the round in the chamber. eject the round, and measure the COL again to see if there is any setback. if there's any set back you may need to adjust your dies.

[Ozzieman]

Depends on if your talking roll crimp or taper.
If you use something other than a taper or factory crimp die you can cause problems if you crimp to much. Since the loaded round seats on the end of case its important that the end of the case is at the right diameter.
I don’t agree with a light crimp or minimal pressure.
I use a taper crimp die on all of my auto rounds that I reload and use a firm crimp. One of the most assured ways to get over pressure is from bullet set back from bullets that are not held to the correct COL.
And as vladan noted about differences in cases, since I taper crimp and crimp with a firm taper I don’t match my brass, and its also why I have loaded thousands of 9mm and never had a failure.
But I have seen the results of a set back in a 10mm case. A friend started reloading 10mm and didn't crimp the bullets hard enough. On the 5 or 6th round he stopped firing because the gun was not "acting" right. When he pulled the round that was in the gun the bullet had been forced into the case by .2 inches. Each and every case that had been fired looked like ++++P rounds.
Granted he shouldn’t have loaded to max pressure on his first rounds but,,,,
Any way, my suggestion is to get a taper crimp die and place a loaded factory round into the press, then set the depth of the taper crimp die until it makes light contact with the loaded factory round and then remove the case. Go 1/4 turn deeper for the die and run all cases through at that setting.
Works for me.

[JT-AR-MG42]

I too have loaded thousands of 9s with no problems using a taper crimp die.

It is worth the extra step and you'll find ALL your loaded rounds will drop into a SAAMI spec. die.

JT

[Citywaterman]

I place a light taper crimp on the 9mm round. The flare may hamper the round from chambering properly. I check chambering by removing the barrel. This works for me.

This round has no crimp and will not chamber. The round should drop in as in the second photo.


This round has the proper taper crimp.



Citywaterman