I always seem to struggle with the amount of taper crimp. It so subjective to me I am just not sure if I put enough or too much. Some have said after putting the crimp on test it by pushing the bullet against the table and see if it sets back further or not. When I reload, I use Redding Competition Bullet Seater followed by the tapered crimp die. After seating the bullet without crimping, the bullet doesn't seem to set back deeper when doing that test and that is without crimping, so it seems even less conclusive when I do the push test after crimping. This makes me worried that I might over compensate and possibly put too much crimp on it. Basically, I am looking for any way that can offer a more scientific/less subjective way to adjust my crimping die. I also wonder what would be a bad outcome or issue that could result from firing loads with too much crimp. Thanks!

For many years I never cripped my auto pistol reloads.

Then I went to a progessive press that had one in the line can't say I can tell much differants.

I think you're vastly over thinking the issue; just 'crimp' them enough to remove the flare.

What type of bullet are you loading, jacketed or lead?
Next question what is the diameter of the bullet?
Next question what diameter does the case flaring punch open the case body? Not the flare at the mouth of the case but down in the body of the case.

Jim
Jim

I use a lee crimp die for my 45 ACP and the case is supported during the crimp so I mash it prety hard.

Cheap die set but I like them for pistol a lot.

A taper crimp is not meant to be applied with gorilla force on the bullet, but rather a gentle holding pressure to keep the bullets from moving under recoil when in the mag. The bullets shouldn't have their shape atlered by the crimp and the case shouldn't have a bulge in the middle from too much crimp. As Jim C. stated "just crimp them enough to remove the flair". If you fire three rounds and examine the cartridges still in the magazine and they haven't changed seating depth you have your crimp, on the other hand if the bullets have moved you need to tighten the crimp but only just a smidge. Then try it again.

I too use the Lee taper crimp dies and they work quite well. Adjust till the die touches the case mouth and another half turn, that's it. You can "fine tune" if you want, but I've never found it to be necessary.

All you need the taper crimp to do is to remove the case mouth flair/belling; no more, no less.

Larry Gibson

don't crimp to much - remember that the case headspaces on the mouth

SAAMI Taper crimp, if you can measure it, is .0002" Or just remove the bell/flare from the case mouth. If rounds dont chamber, apply a hair more taper. Set die to shortest case of the lot. See SAAMI drawing.

I had this same question recently and these guys helped me out. It's more for feeding and reliability. I does keep the bullets from moving during heavy recoil, but if your removing your flaring this is usually accomplished. I was crimping so much that I could see a 1/16 in mark on the cases from the die. This was too much. Crimp till they feed and make sure there not moving in the mag like stated above. Any more than that reduces the working life of your brass, and make for too much trimming.

A .45ACP doesn't produce enough velocity to generate "heavy recoil".

Only the bullet in a chambered cartridge is free to move, all bullets still in the magazine are supported during whatever recoil there is by the front wall of the magazine.

All meaning if we have to 'crimp' a .45ACP bullet to secure it we have worse problems than simple crimping should be asked to fix.

Crimping helps prevent bullet setback caused by bullets smacking the front of the magazine and/or feed ramp. I haven't noticed this with the .45 ACP or the 9mm but it can be a problem with the .357 Sig and the .40 S&W..
C.G.B.

There is a simple test for this. On a 45 ACP the dominate force for bullet movement is feeding. The recoil forces while the round is in the magazine are less. Make up a handful of dummy rounds (no powder, no primer). Put one in the magazine and drop the slide with the slide stop. Repeat five times on the same round and test a few rounds. If the bullet moves you need more crimp, if it doesn't you are good to go (or have too much). Usually enough crimp to take the flare out is enough. If it takes a lot more than that then you are expanding the cases too much. Most of the holding force is the casewall rather than the crimp

0.267 - 0.271 measured at the case mouth

Not on a .45

Also, note that for a given crimp die setting and bullet diameter, a change in case thickness affects how much grip is applied to the bullet. Some cases vary in mouth thickness, so a thicker case has more grip than a thinner one.

I am of the opinion that if the bullet doesn't move in the mag or upon chambering, and all the flare is removed, the crimp is OK.

And there's always the question of "How does it shoot?"

John

Wilson Arms sent me a ammunition data sheet back with a customized M1911.

They advised to taper crimp the mouth of a 45 ACP to 0.469". That is what I crimp to and it works fine in every M1911 and in my Sig 220.

[QUOTE]Originally posted by Jim C. <><:
A .45ACP doesn't produce enough velocity to generate "heavy recoil".

You don't only use TC on a .45 ACP. I was just trying to make the point that TC isn't the be all to end all on securing the bullet. TC in bigger applications like .50 AE then the TC does assist in reducing bullet setback.