A basic crimp question.....

[tjhands]

The data I've read suggests a light crimp for 10mm rounds. My question: how do you crimp a jacketed bullet that doesn't have a cannelure?

When I load .45ACP, I use almost no crimp at all. Do I do the same for 10mm?

Why do bullets designed for revolver use have cannelures whereas ones designed for semi-autos usually have none? Probably a "duh" question, but I had to ask.

 

[capbuster]

Generally cases used in autos are taper crimped and cases for revolvers are rolled crimped. Since revolver headspace on the rim,a roll crimp can be used without affecting this spacing.

 

[Zekewolf]

And, to, hopefully, clarify: Cannelures are for roll crimping. (You "roll" the crimp into the cannelure.) Taper crimping requires no cannelure and is best done by just crimping enough to remove the bell.

 

[tjhands]

Thanks guys. So, basically just do the same for the 10mm as I do for the .45ACP?

 

[mbartel]

A properly made taper crimp die (Lee in my experience) will not put too much taper crimp on the case. A properly functioning extractor will most likely hold the case in place anyway, but the real danger is if somehow an excessively crimped auto case goes into the chamber slightly past the shoulder that determines headspace, and gets wedged so that the case can't properly expand to release the bullet before chamber pressures get dangerously high. A well worn throat on an old autoloader can do this even with factory ammo. If in doubt about the condition of the guns chamber, you should have a qualified gunsmith check it out to determine if it is safe to fire factory ammo.

 

[Ben Shepherd]

Yes basically the same as the 45. Maybe slighty heavier, to help the slower powders the 10mm uses get going, but not much.

 

[Bullet94]

I got this out of one of my loading manuals.

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.

 

[tjhands]

Everyone, thank you.