45 ACP Taper Crimp Spec

Mar 3, 2017
Why can't I find the spec for the taper crimp diameter in my reloading manuals? Is there one? Measuring different factory loads, I'm seeing .469-.472". My brass is around .472 with no crimp. I loaded a couple of rounds with it going to .470 and it puts a small burr on the lip of the case which I'm not crazy about. I can see the shiny folded over lip on the case mouth. I guess I should back it off to around .471?
Nov 10, 2017
Central Montana
My Kimber Team Match with EE has a tight chamber and works great using .469. Larger than that and it has significant extraction problems. The real reason Kimbers external extractor had problems...it wasn't the extractor at all. 25,000 rounds and counting with .469.

I never use factory ammo but it seems to be at .472 and won't work in my Kimber.

My other 1911s can function with the .472 spec that my books show.

I lock the caliper at the desired measurement and adjust the taper crimp until the case just barely enters the caliper.

I would start at .472 and see how it goes but always set with a caliper for reliability. A friend of mine just looks at it.
Likes: treillw


New Hide Member
May 7, 2018
Richmond, Texas
.471 here. I do the plunk test. Remove barrel from pistol, drop round into chamber, tip barrel and round should fall into your hand. If the round sticks, too much crimp. If the round doesn’t go all the way in and make a plunk noise not enough crimp.

Sounds dumb, but has worked in glocks, sigs and my nighthawk.
Mar 3, 2017
So I tried the plunk test. It seems that the less I crimp it, the better it works. Is it bad to have very little to no crimp on the bullets?

When I crimp it further, a small burr develops on the mouth of the case. I feel like my RCBS taper crimp die is behaving kind of like a roll crimp die. I can see a little flat chamfer on the case mouth and feel the burr.

Maybe I am trying to crimp it too hard, to the point where it is distorting the case mouth. It seems like it get the burr with the smallest amount of crimp though. I can see it around .471

My FNX is eating the bullets up either way - I just don't want to damage the brass over time or have the chance at a head spacing issue if the case mouth is ruined. My Kimber 45 seems to have a tighter chamber. I would like the bullets to be interchangeable between guns.

Maybe I hardly have to crimp it at all.... I did not bell the case mouths out terribly to accept the bullet to start with.

Likes: NFAJohn


Gunny Sergeant
May 7, 2009
You only want to bell the case just enough so that the bullet will actually fit in the mouth without crushing the case. Literally a few thousandths. Same thing with crimp. You only want to take the flare out. Adjust your crimp die by inserting a loaded round into the shell holder, raise the ram and screw down the crimp die until it stops on the case mouth. Now lower the ram and screw the crimp die down no more than ¼ turn. You’ll never over crimp that way.
Likes: NFAJohn
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