Belled Crimp

[tegemu]

I am attempting to crimp factory rounds down for better feeding. I am also a neophyte to reloading. I am using a Lee Loadmaster with a Factory Crimp Die, I get a crimp down from .470 t0 .450. My question: I had been expecting a sloped transition down, however I am getting a distinct bell curve. Is this the way it should be? Also, do the dimensions seem OK? Thanks in advance.

[HSMITH]

WHOA!!! Hold up a minute.

What ammo are you crimping and why are you crimping it? What gun are you putting it in? What makes you think the crimp on the factory stuff is inadequate?

A WAG is 45 acp if you started at .470". If you crimped it down to .450" throw it out, you ruined it.

The FCD's I have played with typically taper crimp when set lightly and as you go heavier they eventually begin to roll crimp.

A LOT more information is needed to help you out.

[tegemu]

Let me correct my dimensions. I should have said .407 to ,405. I am crimping SPEER "Lawman". I am having FTF problems on one of my 1911's. The FTF appears to be snagging on the case mouth. As a troubleshooting step I am attempting the additional crimp.

[Sport45]

Like HSMITH asked, what cartridge are you reloading? Nothing comes to mind that would have a case mouth of .405".

[mete]

If you are talking about the 40 S&W ,it , like many auto rounds headspaces on the rim. If you crimp more than the factory crimp it will not headspace properly.I've never heard of factory ammo needing additional crimp.If you take out the barrel your rounds should easily be dropped into the chamber. If so there's nothing wrong with the ammo or chamber.

[Dogjaw]

Sounds more like a fussy 1911 that doesn't like Lawman ammo. The first rule of defensive ammo is that it functions 100% of the time in your weapon. The problem could be the front edge of the bullet itself hanging up on the feed ramp. (Some ammo, even though hollowpoint, is designed to lessen this problem) I'm afraid you could mess around and generate some extra unwanted pressure. Too much of a crimp will also deform the bullet. A light taper crimp is all that's needed on an auto. A "bell crimp" is called a roll crimp and is used on revolver cartridges with rimmed cases. A heavy roll crimp is used on magnum revolver rounds. In my opinion, your best course of action would be to try other loads in your 1911, see what functions reliably, and forget about using Lawman in it.

[tegemu]

I just rechecked the round with my micrometer. Seems I was right the first time. The original dia. was 0.470" and then necks down to 0.450" in a catenary, (bell or elongated "S" curve) in a distance of 0.080" from the start of the bell to the end of the curve. The Bullet Dia. is 0.440". The rounds I am working with are SPEER "Lawman" 230 gr. TMJ, 45 AUTO. My "Complete loading manual for the .45 A.C.P." shows a start dimension of 0.480 case base diameter and my micrometer reading agrees (confirming my Mirometer's accuracy and my reading of it).
So the question is more precisely, Should the crimp be a Catenary Curve for a distance of 0.080" from the lip of the cartridge or a straight line from start to finish of the crimped length? I am surprised to find that the reduction of 0.020' in diameter would permit the round to move forward in the chamber, the cartridge case is still 0.010" wider than the bullet at the lip. But I am such a neophyte that I freely admit that I have a lot to learn - hence this question.

[Sport45]

For 45acp you should not see any discernable "neck" or crimp. The diameter for a jacketed bullet is .451 and should not be reduced by the crimp. I think a .469" diameter at the case mouth is considered adequate (or more than adequate) crimping by most.

[HSMITH]

All the crimp should do on a 45 acp is flatten the case against the bullet shank, that is IT!!!! Doing any more than that will probably wreck accuracy (going down to .450" certainly will) and lower case tension.

45 acp crimps should not form a curve of any sort, the case wall should be straight or very nearly straight. .470" is as small as the case mouth should ever need to go.

In this case your gun or magazines are the problem, not the ammunition.

[brickeyee]

Fix the gun or change ammunition.
This is not a crimp problem, it is a gun problem.
As noted above, the .45 ACP headspaces on the case mouth. If you crimp to far the round will move to deeply intothe chamber and you will have pressure problems when the bullet is wedged into the chamber.

[tegemu]

My sincere thanks for the education. I was pretty sure I should not see a bell, hence the question. I am working on the gun/Ammo possible causes. I feel confident that I can work it out, the extra crimp idea was a "I wonder if this will solve my problem." idea. So much for that idea.

[Sport45]

As noted above, the .45 ACP headspaces on the case mouth. If you crimp to far the round will move to deeply intothe chamber and you will have pressure problems when the bullet is wedged into the chamber.

Absolutely.

Don't even think about firing that cartridge that you over-crimped. The .450" part of the brass will set past the shoulder in the barrel. If you tried to fire that round the .451" bullet would try to swage itself through the ~.430" case mouth you've created. The pressures will be tremendous to say the least. Something will have to give and it will most likely be the chamber or the base of the brass. At the very least hot gasses will be dumped into the magazine well possibly igniting more rounds and certainly splintering the stocks out into your hand. It wouldn't be fun.

Happy shooting and the best of luck in fixing the problem. You might want to post in The Smithy or Semiauto Pistol section as well.