roll/taper crimp 40 s&w


June 15, 2006, 01:29 PM
Guys I need some help, Ive reloaded some lead bullets for my 40 s&w glock, but the crimping is messing me up and most rounds wont chamber. I had it working for a while then something got out of adjustment. The big prob seems that the crimp is right at the edge of the brass and the lead and the lead is getting pushed onto the edge of the brass causeing it to not feed. :cuss: :cuss: :banghead:

Whats the difference between roll crimp and Taper crimp?:confused:

What method do you use for reloading pistol ammo (especially 40 s&w )?

What about loading lead ammo, I do have a custom glock barrel 4 lead.

Please help me figure this out.

Thanks for any info!
:) :)

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The Bushmaster
June 15, 2006, 01:53 PM
Use a light crimp. Don't crimp anymore then it takes to remove the bell.:)

June 15, 2006, 02:13 PM
With the 40 S&W, the "taper crimp" should not be relied upon to hold the bullet - that's not what it's supposed to do. In fact, it isn't really a "crimp" at all. In reality, all the taper crimp should do is to squeeze the top of the case back to the way it was before it went through the expander die. Instead of "taper crimp" they should call it "expansion removal" or something. If you're squeezing lead over the edge of the case, then you are crimping too much.

The friction of the case itself holds the bullet in place. If you need a crimp to hold the bullets (they slide into the case when you push on them) then either your sizing die is worn out or mis-adjusted, or your brass is too thin. I had this problem loading some .32 ACP and 10mm, and asked about it on this very forum. Here's the thread:

Anybody have trouble with Remington brass? (

Member RyanM did a much better job of explaining the effects of too much crimp than I can.

A roll crimp is a different animal altogether. A roll crimp really is a crimp. The top of the case is rolled inward slightly so that the ID of the very top of the case is smaller than what it was when it came out of the sizing die. A roll crimp should only be used on a bullet with a cannelure (a cannelure is a serrated indentation around the diameter of the bullet). The roll crimp rolls the brass into the cannelure and serves to hold the bullet in place. You'll see these on revolver bullets.

Even if your bullets had a cannelure, you probably wouldn't want to use a roll crimp. I believe that in a Glock, the .40 S&W headspaces on the case mouth. If you rolled the mouth into the bullet, you'll get reliability problems.

I hope all this helps.

June 15, 2006, 03:41 PM
Thanks I keep reading on RCBS on how to do the crimp on it gotta figure out how to make the crimp less.. play with it more I guess.. and re-read rcbs instructions on roll crimp i guess ...

June 15, 2006, 07:45 PM

Roll crimps are for revolver rounds, the RCBS 3 die 40S&W carbide set instructions say "Bullets for semi-auto handguns are normally taper crimped because the cartridge headspaces on the case mouth and to assure proper feeding and functioning."

Run an empty case thru the process and observe what happens to the case at each step, set your die up for a roll crimp and process an empty case you'll see what a roll crimp looks like. You do not want a roll crimp for a semi-auto!!

You may want to get a max cartridge case gauge from Midway USA so that you can check your rounds before firing, the gauge isn't much $$ and worth the cost if you load a lot.

Good shooting!

June 15, 2006, 08:28 PM
I shoot a Glock 22 and use Berry's Plated bullets exclusively. I have found that crimping too tight brings on 2 problems, 1 st they do not feed properly (they get hung up 1/2 into the chamber) and 2 nd they keyhole. All you need to do is to remove the bell from the round. Pull a couple of rounds and check if you have a crimp mark in the bullet and readjust accordingly. It is a great gun and a great round, enjoy it.

Matt Dillon
June 16, 2006, 12:14 AM
Get a Lee Factory crimp die for .40 S&W and you won't have any more problems!

June 16, 2006, 11:54 AM
EddieCoyle explained it well.

This is what messed me up the most when I first started reloading. I read about "crimp" and thought that I was supposed to shrink the end of the case to hold the bullet in place. The only "kaboom" I have had in 50K rounds of handloads was due to this error.

With 40's (and 9's and other autoloader rounds), the sizing die shrinks the case down to less than the diameter of the bullet, and you use the least possible expansion or belling of the case mouth, so that the bullet is held in place by the tension of the case neck.

What is meant by "crimp" is that you are removing the belling introduced by the expander die so that the case wall is straight and will feed.

What helped me was to use a micrometer on factory ammo and try to duplicate that. After I started doing that my quality improved considerably.

If you're just starting to reload 40's be aware that they are one of the riskier calibers to reload (IMHO). If you don't get the case neck tension right the bullets can set back while in the gun, increasing the pressure and potentially causing the dreaded "kaboom". This happened to me once, fortunately I was shooting a good quality pistol, an FN Hipower in 40. It blew the grip off the right side of the gun and my hand was numb for a while, but no blood loss and no broken parts in the gun. When I looked at the two remaining cartridges in the magazine half the bullets had disappeared into the brass, they we set back by more than 1/8".

When I'm loading 40's I pay extra careful attention when I set the bullet into the case at the seating stage. If it drops too far into the case I just pull that piece of brass and set it aside. There's normal variation in loading and if it's on the large or loose side I just get rid of it.

Don't get too afraid, I loaded close to 20K rounds of 40 last year without problem, once you get it down it's fast and easy, but there is a learning curve and you need to be aware of the risk factors.

June 16, 2006, 11:53 PM
I am sure you are using a die that crimps and sets the projectile at the same time. They are junk and hard to use. I had the same problem and finally found the fix. Buy a dillion die set from The crimp is a seperate die and they are the esiest dies to ever set up and take apart etc. I battled the same thing youi did for awhile until I bought dillion dies.

June 19, 2006, 04:43 PM
yes I have the RCBS taper crimp die that crimps and seats the bullet at the same time. After much fusteration and about 60 + wasted brass, bullets and primers im ready to buy some other die's because the RCBS taper ones i got simply are not working? Any help or suggestions on what your using.... also note i will be useing this in a hornaday LNL Progressive... Does every one agree with the Dillion taper dies are better over the RCBS taper dies??

Thanks for all your replys!! :)

June 19, 2006, 05:01 PM
Taper crimping is best done with a separate die from the seating die, trying to seat and taper crimp at the same time just doesn't work right. Dillon dies use a completely separate die for taper crimping, but you don't want Dillon pistol dies unless you have a Dillon press, on Dillon presses the case mouth is expanded when going through the powder measure, so Dillon dies don't include a die for expanding the case mouth.

June 19, 2006, 05:18 PM
so what die do you recommend. the Lee crimp die with what other die to seat??

June 19, 2006, 08:52 PM
Get the Lee factory crimp die and then use your RCBS seater/crimper die to just seat the bullet. Basically just back off the die and screw down the seater plug til it's just seating the bullet to the right depth.

You don't have to buy a whole new set of dies.

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