Taper or Roll Crimp - 357 Mag.


January 26, 2003, 10:57 AM
Need some quick help here. I received a set of RCBS 357 mag dies marked TC which I just found out is for taper crimp. I want to shoot H110 powder with a Hornady 158 gr. XTP out of my 357 mag revolver.

Should I try taper crimping or send them back and get the roll crimp die set? I believe the answer is roll crimp but I don't know much about taper crimping other than it applies to more of a semi-auto pistol than revolver setup.


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January 26, 2003, 11:36 AM
Send it back. You need a good strong roll crimp with H110.


January 26, 2003, 12:34 PM
Actually, I have shot the 357 using both crimps, and did not have any trouble with either......they both shot well, and no bullet pull out with recoil..........but, they do recommend a good roll crimp with 357 mags...........

January 26, 2003, 04:17 PM
ADD a Redding Profile crimp die.

January 26, 2003, 04:34 PM
I second the profile crimp die, particularly if you're using a progressive press.

A bit odd to setup, but it crimps like mad ;-)

Paul "Fitz" Jones
January 26, 2003, 05:02 PM
Lead bullets of 158 grain weight have a roll crimp groove as part of their design. The .357 mag round can create heavy recoil and the roll crimp is to keep bullets from moving forward and keeping the revolver cylinder from rotating to the next round. Also in lever action rifles like an 1892 Winchester or copies the rounds are in a tubular magazine and each round that is fired affects each round in the magazine. The heaviness of the crimp whether in a lead or jacketed bullet is to keep the bullet from moving for safety. In jacketed bullets used in loaded ammo there may be a cannelure which is a rolled depression created in the case behind the bullet to keep it from moving back in the case during recoil and from the column of rounds in the rifle magazine also.

Fired brass can be "Read" to indicate what bullets were fired from it. The expected life of the casing is also shown by the placement of the cannelure on the casing. A cannelure close to the mouth of the casing indicates a light bullet was fired at high velocity stressing the casing and reducing its life for reloading as it will split to the cannelure soon. A casing without a cannelure or one with the cannelure the fartherest back had a lesser power load and will last the longest in reloading without splitting.

Many available jacketed rifle and pistol bullets have a cannelure rolled onto the bullet for the casing to be roll crimped into. The cannelure on those jacketed bullets indicates that those bullets were designed for higher velocities or in tubular magazine weapons.

January 27, 2003, 06:10 AM
I have tried both and I am back to roll crimping revolver rounds. The only thing the taper crimp is good for with revolvers is plated bullets.

January 27, 2003, 08:38 AM
The RCBS carbide taper crimp dies are going back. Should have a new set of dies by tomorrow.

Those Redding profile crimp dies have me interested. What advantages do they offer over the RCBS carbide die set???


January 27, 2003, 11:06 AM
As I understand it (and from what I've observed, using the Profile Crimp).. It first applies a slight taper crimp, which assures the bullet is tight in the case mouth itself, and then applies a light roll-crimp just to make sure.

January 27, 2003, 11:15 AM
To apply a taper crimp first then a roll crimp.....what is the advantage over just applying a roll crimp?


February 1, 2003, 01:52 PM
The taper crimp has one major advantage over the roll crimp.

With the roll crimp, the brass must be exactly the same lenth to ensure that every crimp has the same "roll" to it. Get different lenths of cases and you will have rolls that are not the same.

With a taper die, this is not so criticle. As Mr. Fitz has stated, many bullet designs have a roll crimp groove buit into them. To taper crimp these designs, you just move the bullet a litte farther out.

As for the taper crimp being weaker...I dont think so. Test it yourself. Get a kinetic bullet puller and try to bull a taper crimp and compare it to the effort expended on a roll crimp. You might be suprised at the amount of effort expended on the taper as compared to the crimp.

The progressive press is better with a taper crimp due to the differences in lenth. Most of you are familiar wiht Dillion equipment. Do you really think that he would include taper crimps on his dies if they were not the best ?

I gave up roll crimping a long time ago. The taper crimp holds well, works the brass less and seems to be more accurate. I've loaded thosands of rounds of each caliber and have yet to experience setback in either pistol or revolver. I too used to be somewhat cautious of "taper" crimping when they first came out, but experience has shown me otherwise.:what:

February 1, 2003, 05:18 PM
Roll crimp will do the best.

Paul "Fitz" Jones
February 1, 2003, 11:02 PM
Basically Roll crimps are for high power loads where there is concern that bullets will move out of their proper position in cartridges during the recoil of firing nearby other cartridges.

Taper crimping was invented for lower powered target cartridges and is commonly used in progressive reloading machines by target competitors needing a large volume of rounds.

Some full powered 45acp loads are taper crimped by combat shooters however so either type of crimping can be used as long as it suits you and your style of shooting.

Nuff Said.

Paul Jones

February 2, 2003, 02:47 PM
it has always been my understanding that taper crimp was for semi autos, and roll crimps are used for Revolver cartridges. I use RCBS dies, and the .45 auto, 9mm, and .40 are marked 'tc' on them.

February 2, 2003, 03:35 PM
I have 9mm,.357,.40,.44 mag,.45 Long Colt, and .45 ACP.

All are Dillon dies, all have taper crimp.

I have used H110 and WW 296 along with AA #9 on the .44 mag with absolutley no problems. Ditto for the .357.

I continue to hear lots of myths about both the roll and the taper crimp. Fact of the matter is, I got rid of my roll crimp dies and went exclusively to taper crimp.

The main reason for this was the unequal lenths of brass that you must deal with to ensure the crimp is the same. In the summer time when I go play at the gunclub, it was not uncommon for me to go though several hundred rounds a week.

Using the taper crimp save lots of time by not having to trim the brass.

I use everything from light loads to punch paper, to heavy deer hunting loads with the .44 mag and everything in between

I have never had a setback with taper crimps on a revolver or semi auto.

You couldnt PAY me to go back to roll crimps.

Im quite shocked to find out Ive been doing it wrong all of these years.

Bill Adair
February 2, 2003, 07:16 PM

I have both, and use them according to the bullet type.

For bullets with a crimp groove, the roll crimp is used, but for plated bullets, and other bullets without a crimp groove, a taper crimp is best.

The idea is to crimp without deforming the bullets, which could effect accuracy.

Even too heavy a taper crimp can deform bullets, so I only use enough to remove the flare, and snug the case mouth tight to the bullet jacket, or plating.

You can still buy a taper crimp die separately, and Lee has them at reasonable prices. I bought an RCBS taper crimp die, because RCBS is all I've ever used, and I'm quite happy with them. :)


February 2, 2003, 07:47 PM
I sent the RCBS taper crimp die set back and received the roll crimp die set. This has been a good discussion and very interesting in regards to taper vs roll crimp. I have learned alot.


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