9mm crimp measurement

[1911WB]

Anyone know what the ideal crimp measurement should be for 9mm cast 122 gr. bullets (.356)? I have been handloading for a number of years, but have only recently gotten into 9mm loading, and more recently into 9mm cast bullets. Thanks for any helpful advice.

 

[griz]

Not sure which measurement you mean. I just set up to remove the tiny bit of flare and have never had a problem.

 

[MP-5]

I dont load lead in 9mm but I use a light crimp .376-.378.

 

[callgood]

I have crimped cast .45ACP using Precision Bullets. These are lead bullets covered with a black, slick "plastic" coating. I have also crimped 10mm jacketed, using my Lee FDC roll crimp for both types. I used one full turn after making contact with the bullet. I tried to back off to 3/4 on the jacketed, but my Glock wouldn't go into battery. I had to bump the rear of the slide with my thumb to engage. The Precision Bullets cast worked fine and gave good groups.
I read just recently that crimping TOO tight on cast can cause an "undercrimp" in that the brass will snap back but the lead will not.

 

[HSMITH]

Like griz said, just take the bell out of the case.

 

[MP-5]

Griz & HSmith,

The measurement 1911WB is refering to the crimp or the measurement of the case "crimped" or folded inward towards the bullet to keep it in place. The "belling" or flairing of the case mouth is a different step in the reload process which happens before seating the bullet while crimping usually happens after the bullet is seated.

 

[The Bushmaster]

Griz has it right. Especially if you are loading jacketed bullets. I also only bell the 9mm case just enough to start the bullet and just remove what bell that is left. I do my .45 ACPs the same way without any problems such as "set back". And I load . 45 ACPs rather hot. If the bullet tention to case is as it should be that should suffice. I fear that any added crimp would place the case into the chamber too far creating a high pressure. Remember the mouth of the case is what keeps the case and bullet in proper relation to the bolt face and not into the rifling where it could also be a problem.

 

[Bullet]

Taper crimping should remove any flare left on the case mouth from the neck expanding step and squeeze in the case mouth tightly against the bullet. After the flare is removed from the case mouth the case should not be reduced in diameter by more than .001” or .002”. Any more than this, and the bullet will be deformed in this area. Of course accuracy will then be effected. Cast bullets, especially when made from a soft alloy, are particularly vulnerable.

This is a QUOTE from one of my loading manuals.