Too much crimp?

SpyderMan2k4 · September 21, 2006, 07:08 PM

Hey everyone,

This past weekend I loaded my first rounds of 45 ACP. I know all about the problems of undercrimping, but are there any issues with over crimping? What are the signs of an over crimp? Will it be dangerous, or just affect accuracy, or neither? Both? Any information would be great. Thank you!

Chris W · September 21, 2006, 07:19 PM

With most bullets, your first sign of overcrimping will be that the case buckles. I.e., you press down so hard on the mouth in your crimping mania

that you force it to start to collapse. So the cartridge case is out of spec, and it won't chamber.

If you're using plated bullets, you need to run real light on crimping. They generally don't have a cannelure, and if you break through the thin copper plating with the case mouth, it may effect accuracy.

HSMITH · September 21, 2006, 07:39 PM

The only problem you will have from undercrimping 45 acp is function. The bell on the case will keep the gun from cycling. That is IT!

Overcrimping is anything more than just putting the case mouth back in contact with the bullet. Depending on how much you overcrimp the problems can be pretty varied. Bullet setback and poor accuracy are very common problems with an excessive crimp.

Chris W · September 21, 2006, 07:49 PM

Well, okay, in a .45acp, yeah.

I have found that a little more energetic crimp (together with good neck tension) help things along in a magnum cartridge with a slow-burning powder. But that's probly useless obfuscation (a whole separate hobby of mine) in this context.

Vitamin G · September 21, 2006, 10:36 PM

My first overcrimped rounds wouldn't feed... Either way, too _____ crimp is bad. I just take the belling out, and i dont need a FCD

Dave Haven · September 22, 2006, 12:32 AM

I've never crimped .45ACP or 9mm Parabellum. If I needed to crimp them I overexpanded them...

amamnn · September 22, 2006, 06:24 PM

It's hard, but not impossible to get a good feel for the crimp if you try to do it using the seating die. It's easier to control the crimp in a separate operation. Also, it is hard to get a consistent crimp pressure from most presses. Admittedly, this is not crucial to most handgun shooters, but it's good practice to try to make your handgun loads as accuately as you make your 6mm ppc loads.....................
I like the Lee factory crimp die for rifle plinking/hunting loads and hanndgun autoloaders and the Redding profile crimper for revolver loads. Before I got my Forster co-ax press I tried several methods for making uniform crimps, including using a large fish scale to measure the pressure on the press handle. Needless to say, none were very successful. Still, the crimp can make a big difference in start pressure in any load, so uniformity is worth pursuing.
In autoloading handgun loads, overcrimping is not really a problem (other than with accuracy) until and unless it gets to the point of distorting the bullet as noted in a post above. Hopefully, it would have been noticed and dealt with before it came to this point.

Ammo Junky · September 24, 2006, 07:04 PM

If I needed to crimp them I overexpanded them...

+1

Mag revolver is a different story, well sometimes.

I load full power H110 loads in my 480 ruger with only a taper crimp on 325gr ranier bullets and they chrono the same as the gold dots with a crimp. They do scoot a few thousands, but not enough to effect accuracy or function.

clayking · September 24, 2006, 08:07 PM

I recently set my .45 crimp snug enough so that they would load into a .45 revolver. With a light crimp they would not fully seat. I kept giving a 1/8 turn down on the crimp until they dropped into the cylinder. Later I shot them in my auto and they did fine, grouped as well as before the tighter crimp. An excessive crimp would rise pressure..............ck

kansas45 · September 24, 2006, 09:42 PM

I was told that .001/.002" is about right for 45acp. I've been doing that & even as much as.0035 without any trouble.

SpyderMan2k4 · September 24, 2006, 09:53 PM

Well, I found out this past weekend first hand (before I could get back online and read this stuff! lol) That overcrimping will cause feeding problems. My first batch of ammo wouldn't feed. At first I thought it was the COL rather than the crimp, but talking with some people and doing some other tests, I concluded that it was excessive crimp. I lessened it on my original COL, and the bullets fired perfect.

September 21, 2006, 07:08 PM	#1
SpyderMan2k4 Member Join Date: August 6, 2006 Posts: 35	Too much crimp? Hey everyone, This past weekend I loaded my first rounds of 45 ACP. I know all about the problems of undercrimping, but are there any issues with over crimping? What are the signs of an over crimp? Will it be dangerous, or just affect accuracy, or neither? Both? Any information would be great. Thank you!

September 21, 2006, 07:19 PM	#2
Chris W Senior Member Join Date: May 5, 2002 Location: Central WA Posts: 450	With most bullets, your first sign of overcrimping will be that the case buckles. I.e., you press down so hard on the mouth in your crimping mania that you force it to start to collapse. So the cartridge case is out of spec, and it won't chamber. If you're using plated bullets, you need to run real light on crimping. They generally don't have a cannelure, and if you break through the thin copper plating with the case mouth, it may effect accuracy.

September 21, 2006, 07:39 PM	#3
HSMITH Senior Member Join Date: June 22, 2002 Posts: 2,019	The only problem you will have from undercrimping 45 acp is function. The bell on the case will keep the gun from cycling. That is IT! Overcrimping is anything more than just putting the case mouth back in contact with the bullet. Depending on how much you overcrimp the problems can be pretty varied. Bullet setback and poor accuracy are very common problems with an excessive crimp.

September 21, 2006, 07:49 PM	#4
Chris W Senior Member Join Date: May 5, 2002 Location: Central WA Posts: 450	Well, okay, in a .45acp, yeah. I have found that a little more energetic crimp (together with good neck tension) help things along in a magnum cartridge with a slow-burning powder. But that's probly useless obfuscation (a whole separate hobby of mine) in this context.

September 21, 2006, 10:36 PM	#5
Vitamin G Senior Member Join Date: May 25, 2004 Location: Pittsburgh, PA Posts: 307	My first overcrimped rounds wouldn't feed... Either way, too _____ crimp is bad. I just take the belling out, and i dont need a FCD

September 22, 2006, 12:32 AM	#6
Dave Haven Senior Member Join Date: February 1, 2000 Location: near Flagstaff, AZ Posts: 790	I've never crimped .45ACP or 9mm Parabellum. If I needed to crimp them I overexpanded them...

September 22, 2006, 06:24 PM	#7
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	It's hard, but not impossible to get a good feel for the crimp if you try to do it using the seating die. It's easier to control the crimp in a separate operation. Also, it is hard to get a consistent crimp pressure from most presses. Admittedly, this is not crucial to most handgun shooters, but it's good practice to try to make your handgun loads as accuately as you make your 6mm ppc loads..................... I like the Lee factory crimp die for rifle plinking/hunting loads and hanndgun autoloaders and the Redding profile crimper for revolver loads. Before I got my Forster co-ax press I tried several methods for making uniform crimps, including using a large fish scale to measure the pressure on the press handle. Needless to say, none were very successful. Still, the crimp can make a big difference in start pressure in any load, so uniformity is worth pursuing. In autoloading handgun loads, overcrimping is not really a problem (other than with accuracy) until and unless it gets to the point of distorting the bullet as noted in a post above. Hopefully, it would have been noticed and dealt with before it came to this point.

September 24, 2006, 07:04 PM	#8
Ammo Junky Senior Member Join Date: March 11, 2006 Location: IL Posts: 537	If I needed to crimp them I overexpanded them... +1 Mag revolver is a different story, well sometimes. I load full power H110 loads in my 480 ruger with only a taper crimp on 325gr ranier bullets and they chrono the same as the gold dots with a crimp. They do scoot a few thousands, but not enough to effect accuracy or function.

September 24, 2006, 08:07 PM	#9
clayking Senior Member Join Date: January 29, 2006 Location: Florida Posts: 796	I recently set my .45 crimp snug enough so that they would load into a .45 revolver. With a light crimp they would not fully seat. I kept giving a 1/8 turn down on the crimp until they dropped into the cylinder. Later I shot them in my auto and they did fine, grouped as well as before the tighter crimp. An excessive crimp would rise pressure..............ck

September 24, 2006, 09:42 PM	#10
kansas45 Senior Member Join Date: June 25, 2006 Location: Southern Kansas, near I-35 Posts: 142	I was told that .001/.002" is about right for 45acp. I've been doing that & even as much as.0035 without any trouble.

September 24, 2006, 09:53 PM	#11
SpyderMan2k4 Member Join Date: August 6, 2006 Posts: 35	Well, I found out this past weekend first hand (before I could get back online and read this stuff! lol) That overcrimping will cause feeding problems. My first batch of ammo wouldn't feed. At first I thought it was the COL rather than the crimp, but talking with some people and doing some other tests, I concluded that it was excessive crimp. I lessened it on my original COL, and the bullets fired perfect.