Reloading and crimps

[AIRret]

Which crimp do we need for reloading 9mm, 38 special, 45acp,and 380? We see taper or rolled crimps listed.

[Tilos]

Except for the 38, the case mouth determines the "headspace" on autos and actually needs no crimp per say.
Just straightened out to remove any bell mouth/flare created to aid in bullet seating.
...jmo
Tilos

[Bawanna]

To expand on Tilos's spot on correct answer, the 38 has a rim on the case that positions it correctly in the cylinder. The others the case mouth prevents the case from going too deep in the chamber.

You can roll crimp the 38. I prefer not to over crimp but it would vary between say lead bullets and jacketed bullets. Some 38/357 bullets have cannelures, those are made to be roll crimped into that little groove.

I taper crimp autos just to make sure but not much.

[OldLincoln]

Taper crimp for most autos - all Kahrs. That new Boberg may need rolled crimp but haven't heard. The rolled crimp kinda bites into the bullet at the mouth of the case primarily to keep the bullet from separating from the case. This is a big deal for revolvers where the fresh rounds are exposed to the full recoil. The taper just snugs the bullet into a nice hug as the fresh rounds are in a magazine below the violence of recoil.

[AIRret]

Folks, Thanks for the good information, especially about the difference between a revolver and an automatic.
Hey Lincoln, my husband and I were just talking about the Boberg (we should have had ours already but we are still on the road) and crimping. Because as you obviously already know the bullets are extracted backwards before they are feed into the chamber. So this may present some special issues. We will put at least 1,000 rounds of factory ammo through the Boberg before we try reloads.
This is a great forum, you folks are very helpful. Thanks for letting me learn from you.

[Bawanna]

I submit that the Boberg could benefit from a roll crimp but it's still an auto and the headspace will be negatively impacted if you roll crimp ammo for it.
A good taper crimp is all you can do for it.

[TheTman]

The Boberg XR9S manual states "NEVER use non-standard or reloaded ammunition."
Doing so will void your warranty (Per Arne Boberg on his forum). If it were a $300 gun, I wouldn't worry about it, but at the price they go for, and it being such an unique design, I'd hate to void my warranty just to save a couple bucks. It shoots Wally World cheap WWB fine, so why take a chance. JMHO
There are still only around 500-700 Bobergs out there, and the design hasn't had the chance to show any flaws that might creep up after a couple years. I definately want my warranty intact.

[ez9]

i have crimp die for 380(lee), just makes it a real nice finish, but have shot without crimp also. Thinking about getting a 9 mm crimp die for that fine finish. All my 9's have not been crimped and i dont like crimping with seat die. I think crimp die does not bother top rim of 9 shell. With a rough place i just touch a few passes with fine fingernail file. I have been shooting lead (&copper plated) thru my kahrs with no problem.

[jg rider]

AFAIK all auto rnds. like .380, 9mm, 38 supper, .40, 45 acp all use a taper crimp because these rounds head space on the case mouth, meaning that's what stops the case from going any further into the chamber as the breach face of the slide holds the case in place. IIRC now match barrels for 38 supers head space on the semi rims. All the bullets for these rounds don't have a crimp groove in the bullet for a rolled crimp to go into. If you try to roll crimp these, one of two things happen, you cause a groove to form in the bullet sides as the case mouth pushes in, this can cause excessive pressures. Or the other thing is if the case mouth doesn't push into the bullet then a bulge forms around the case mouth causing a possible failure to chamber.

IMHO only revolvers rounds need roll crimps because the bullet either have a cannelures or crimp grooves.
AFAIK the reason for a roll crimp is:

I don't know what I was talking about. Read the next post

This is true with +p or magnum loads.

That's my story and I'm sticking to it

[Tilos]

jg rider:
Thanks for confirming what has been posted, except near the end when you got to that revolver and the bullet setting back part, as it does not re-act to recoil as you described.
Heavy recoil, in a revolver, will increase the overall length of the remaining rounds, if they are not heavily crimped, more so with lighter bullets, and actually extend beyond the cylinder and restrict it from turning.
Tilos

[jg rider]

jg rider:
Thanks for confirming what has been posted, except near the end when you got to that revolver and the bullet setting back part, as it does not re-act to recoil as you described.
Heavy recoil, in a revolver, will increase the overall length of the remaining rounds, if they are not heavily crimped, more so with lighter bullets, and actually extend beyond the cylinder and restrict it from turning.
Tilos

Duh! you're right. Would you believe it was a test? I don't know what I was thinking. I have excessive pressure on the brain. I have personal experiance with what you're saying. I have a S&W 342 Ti that does just that with my cast bullets.

[tarheelcm9]

When I reloaded 45 ACP I didn't use any kind of crimp. I have the cheap LEE carbide dies , but they worked fine. Just a full length sizing and neck expanding is all that I did to the cases.