Using an M-die for my .45acp... Do I Need to crimp?

[lts70]

I was having problems with my 9mm loads and to solve the problems I had to get a M-die...no problems with leading now as the case does not swage down the boolit diemater anymore.

Well at the time I ordered the m-die for my 9mm setup I decided to go ahead and buy one for my 45acp setup.

I was loading a new RN boolit design for the first time last night ( got an awesome RN 5 cavity with one of the cavities HP from Swede Nelson NOE). After I got the bullet seated I took the barrel out of my 1911 to make sure it cambered to the right depth and it slide in like I had already used my crimp die to kiss the bell out...but I had not. With my old expanding die it would have never cambered until I took the bell out with the crimp die.

I had borrowed out my calibers to a friend so I couldn’t check the diameter. But if it chambers just fine do I even need to run it through my crimp die? Is this common with the m-die?

[Echo]

Not common IME, but if it chambers, shoot it.

[Iron Mike Golf]

I'd crimp it. You lose a little neck tension. How much will vary with the depth of the expander setting and case wall thickness. You might run into some brass where the case wall thickness is enough that with the second step of expansion, the round could have difficulty chambering.

Common? Dunno. I never skipped crimping. I'd expect mileage to vary with gun and headstamp.

[runfiverun]

i'd be more worried about shoving the boolit into the case deeper..
strip one from the mag into the chamber a few times and measure the oal..

[lts70]

I was under the impression that a 45acp case was not to be crimped with cast boolits. Instead you where to make the case straight, just enough to chamber. Should I be crimping to hold the boolit attached to the case?

[mpmarty]

Never roll crimp a round for an autoloading pistol. Taper crimp just enough to make the brass straight and iron out any bell.

[lts70]

I am interested to check things out with my calipers tonight. Does the m-die bell the case or does it expand in a straight fashion?

[462]

"Does the m-die bell the case or does it expand in a straight fashion?"

Both, depending on how you adjust the die.

[Mk42gunner]

This has been gone over a few times. While the "best" way is to use a taper crimp, you can use a slight roll crimp on the .45 ACP; after all that was the only crimp style available until sometime in the 1970's or 80's, IIRC.

The easiest way I found to set the amount of taper crimp is to use a factory loaded ball round and screw the crimp die down until it just touches it. a lot of people used to use a GI ball round, but since they aren't that common anymore, I use one from Winchester with absolutely no problems.

Robert

[35remington]

SAAMI spec for maximum diameter of the case mouth with a bullet in place is .473." If yours exceed this, you should be crimping them. Check with your calipers.

It is a reliability aid that ensures full chambering without the case hanging up and refusing to go fully into battery.

In the commonly recommended diameters to "crimp to" which is in the vicinity of .470" the taper crimp offers absolutely no help in holding the bullet in place.

[williamwaco]

The .45ACP headspaces on the mouth of the case.

It should be crimped just enough to make the walls straight but you should have a flat surface at the mouth of the case. The mouth of the case should not be crimped enough to allow it to enter the rifling.

[Sonnypie]

This is why I have old factory military loads I use for reference when setting dies.
Helps me get right on a Gnat's A.... tail feathers, easily and readily.
Most immediate example? I found the die set I'd been missing the other day. In setting up the press with the RCBS TC dies, I made sure the dies were right on to original specs. (They were)
In my case, 1934 Military Ball Ammo spec's.

It is prudent to retain some ammunition you know works, beyond any doubt, for reference rounds to use when setting up, checking, or testing.

And learn to not loan out things you do not want botched up. ;-) :violin:

[9.3X62AL]

Lotta good info above.

All I can add for the benefit of folks that like to set a MONDO FIRM taper crimp.....go slowly in this process, because while the brass has some spring-back after radial compression--the lead boolit has far less, and you could in effect be "loosening" case mouth grip on your boolit. I have seen this more often with the 9mm and its tapered case than in 40 S&W or 45 ACP, but the potential to cause this anomaly is always present if a taper-crimp die step is "over-applied". And ALWAYS taper-crimp a cast boolit in a seperate die step after seating--taper crimp seating dies are tools of the devil. Hate 'em.