Help me understand when to and what type of bullets to crimp

[762NATO]

I only have one reloading manual so far (Lyman) and it says that ammo being used in revolvers, semi-auto, and tubular magazine-fed firearms should be crimped. It also says that you should only crimp bullets with cannelure. I'm looking at a lot of the pistol bullets out there and a lot of them don't appear to have cannelures. So it seems like I can't follow Lyman's advice!

Also, for some reason I'm thinking that taper crimping wouldn't require a cannelure whereas roll crimping would (though I'm probably wrong!). I'm trying to decide on a die set for my 40S&Ws and I've been looking at the Dillon and Hornady sets. Both sets feature roll crimping. Is this what I want?

Also, I'm getting the Forster rifle dies for my .308 (M14). They do not crimp. Any recommendations on a crimp-only die for .308?

 

[rcmodel]

In general, you roll-crimp revolvers and taper-crimp auto pistols.

The autos headspace on the case mouth, so you cannot roll crimp them.

Despite what Dillon & Hornady say about their dies for .40 S&W, they must do a taper crimp.

If you are looking at .308 Full Length sizing die sets for an M1A that doesn't crimp, you are looking at the wrong brand of dies.

rc

 

[dagger dog]

Your 40S&W head spaces on the case mouth so a taper crimp is need to keep the head space correct.

Your M14 could be shot single shot with no crimp, but if loading the magazine you might want to use a .308 caliber bullet with a cannelure to keep the rounds in the mag from slipping their bullets from recoil, but if you have the neck tension on the die set tight enough on the 14 you my not have to crimp.

Lee offers a "factory crimp" die some have had good things to say about this system, but I don't like deforming a bullet as this die forces a "cannelure" into the bullet.

 

[762NATO]

Right...I forgot about headspacing from the mouth. I would have caught that when re-reading the manual before performing any actual reloading.

So bullets don't require a cannelure for taper crimping?

If you are looking at .308 Full Length sizing die sets for an M1A that doesn't crimp, you are looking at the wrong brand of dies.

My friend shoots high power matches with his M1A and does not crimp for accuracy purposes. If I was making match ammo, I wouldn't crimp either. That day may come. For now, ammo is for blasting, hunting and SHTF. The latter two may cause rounds to get excessively knocked around, which is why I would like to crimp. I'd just prefer to crimp in a separate step from sizing.

 

[762NATO]

Your M14 could be shot single shot with no crimp, but if loading the magazine you might want to use a .308 caliber bullet with a cannelure to keep the rounds in the mag from slipping their bullets from recoil, but if you have the neck tension on the die set tight enough on the 14 you my not have to crimp.

Lee offers a "factory crimp" die some have had good things to say about this system, but I don't like deforming a bullet as this die forces a "cannelure" into the bullet.

LOL, that would be a pain because you'd have to drop them one at a time into the magazine since you cannot load a round directly into the chamber of an M14 without (high) risk of an out-of-battery slam fire.

If that's what the Lee FCD does, I don't think I'm interested. I'd like as little crimp as possible. But of course, I'm sure they created the die for a reason. Maybe I'll find that out once I actually start reloading.

 

[Walkalong]

Taper crimping does not require a cannelure. You can taper crimp bullets with cannelures if you want to.

 

[ranger335v]

"I only have one reloading manual so far (Lyman) and it says that ammo being used in revolvers, semi-auto, and tubular magazine-fed firearms should be crimped. It also says that you should only crimp bullets with cannelure."

Do it Lyman's way and all will be well.

 

[1SOW]

Taking out the case mouth 'flare' for straight wall pistol ammo is still called 'crimping'---taper crimping. All metallic ammo is crimped like the manual said..

So the 'type' of crimp changes with the bullet type and caliber--taper crimp, roll crimp, etc.