Roll crimp vs Taper Crimp for Revolver Loads

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Roll crimp vs Taper Crimp for Revolver Loads

Post by chiltech500 on Tue Aug 05, 2014 4:28 pm

In looking at and talking about revolver loads I have seen suggestions of roll crimps rather than taper for revolvers.

What say the experts here. I have been shooting a 45 acp Ruger with taper crimped loads because that's all I have on my Dillon 550. Just received my 38sp dies and I am assuming it is a taper crimp as well.

While we're talking about it on a .358 DEWC what kind of OAL and crimp should I be looking at? I have heard just enough wadcutter so it peaks over the edge (terminology?) of the case. Any suggestions a tad more scientific sounding? Smile

Thanks

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by LenV on Tue Aug 05, 2014 5:18 pm

If the pistol bullet has no cannelure then use a taper crimp. If it has a cannelure then use a roll crimp. That is pretty simplistic of an answer but in my experience that's what works. That doesn't answer your other questions but its a start.

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by JIMPGOV on Tue Aug 05, 2014 8:45 pm

LOADIN WADCUTTERS ?? JUST WHAT I'VE FOUND. I PERSONALLY USE HBWC SWAGED EXCLUSIVELY NOW. BUT I HAVE IN THE PAST LOADED PLENTY OF DEWC. DEWC MOST HAVE A SMALL NUB. LOAD THAT AS THE FRONT OF THE BULLET.  I LOAD ALL WADCUTTERS JUST BELOW FLUSH AND USE THE REDDING PROFILE CRIMP . IT IS A COMBO OF TAPER AND SLIGHT ROLL. THAT IS A 24 SHOT GROUP AT 50YDS. 24 SHOTS IS BECAUSE THATS WHAT WE SHOOT AT 50 YDS IN PPC. THAT WAS FROM THE RANSOM REST IN LESS THAN FAVORABLE CONDITIONS. 2.7GR WST ZERO OR REMINGTON 148GR HBWC. JIM P
 photo sdc11114.jpg

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by james r chapman on Tue Aug 05, 2014 9:10 pm

Remington uses a roll on their .38 match target loads.

Precision Delta uses a roll crimp on their championship winning loads.

All are rolled at or over the bullet edge.

Mine do the same.  Smile


Ps; is that a Mojo from Leininger?

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by Rob Kovach on Tue Aug 05, 2014 11:59 pm

I'm going to try the Lee Factory Crimp on my .38s.

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by Fire Escape on Wed Aug 06, 2014 4:36 pm

I believe that the "type" of crimp has more to do with the firearm the cartridge will be fired in than the caliber, cartridge name, etc.
The rounds act differently in different types of firearms. In an auto loading pistol the crimp is MOSTLY intended to prevent the bullet from telescoping back into the case (as it contacts the feed ramp) which will reduce volume and increase presure. A taper type of crimp will press the edge of the case into the side of the bullet to reduce movement backward by the bullet and still leave some 'edge' of the case mouth exposed to headspace in the chamber. With a revolver, the bullet will 'want' to move forward in response to the recoil effect of the other cartridges being fired (more correctly, the bullet by it's inertia, tends to stay in one place while the firearm and cartridge case move to the rear). A roll crimp can provide more resistance to movement in this direction (from which the handgun could become 'locked-up' by a bullet protruding from the front of the cylinder) and since most revolver cartridges headspace on the rim rather than case mouth, it doesn't matter if any of that mouth is left exposed beyond the 'side' of the bullet to headspace on. Bullets intended for revolver use generally have a crimping groove.
When you get into loading wad cutter bullets for auto-loading guns, there really isn't any bullet exposed beyond the cartridge mouth to be pushed deeper into the case so crimp mostly matters as to keeping the bullet from falling out of the case in handling and in head spacing. Since many auto loaders headspace on the extractor (not to say that this is preffered) as much as the case mouth, most any crimp will 'work' though I would still go with taper. Wad cutter bullets in a revolver, are not really different from any other bullet, they just need enough crimp to keep from migrating forward, the shape of the roll crimp is more suited to prevent forward bullet motion and is usually what is supplied with die sets intended for revolver use. Crimping certainly does have an effect on how quickly the bullet can start moving and how the pressure builds as the cartridge is fired, this is more a matter of the degree of crimp than it's shape although everything is related.
Probably over simplified and certainly not covering all possibilities, that is my opinion and it's worth everything you paid for it!

Bruce

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by chiltech500 on Wed Aug 06, 2014 7:45 pm

Thanks so much for the responses. I've been told on another forum that most likely a roll crimp came with the die set I ordered from Dillon for 38sp.

I will have to post a picture and ask questions based on that, because this is an instance where a picture is worth...

Great explanation Bruce. Sounds like I should  get a roll crimp for my 45 rounds that will be shot out of a revolver. As mentioned earlier, the 45 acp LSWC have been shot with a taper crimp mostly out of 1911's until recently I acquired a revolver.

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by Fire Escape on Wed Aug 06, 2014 8:41 pm

Shooting Bullseye level loads from your revolver may not require any more crimp than you have been using (or could adjust your die to). I have heard (I know, heresay) that a reasonable test of crimp with revolver loads is to have a bullet stay in place through the firing of two cylinders full of the same load. Load up the gun, shoot five, mark the remaining round, replace the fired ones and fire all but the marked round. Then compare the length of the 'test round' with fresh rounds to see if the bullet is creeping. If you were assembling 'bear loads' I would definitely change to a roll crimp but you are not stretching the envelope much with target loads so you may not have anything broken to be fixed.

Bruce

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Re: Roll crimp vs Taper Crimp for Revolver Loads

Post by knightimac on Thu Aug 07, 2014 10:54 am

Hi

My sugestion is to put a good taper crimp on the 45 if shooting 200 gr swc.  Using the same ammo you used in your 45 auto is just fine. 

I also suggest putting good roll crimp on .38 if shooting 158gr lead swc with a crimp groove.  38 dies are made to roll crimp.  If you make little rings of metal when runny dummy rounds thru while setting the roll crimp, it's way to much.  Back off until that ceases.


You do NOT want uncrimped bullets coming forward in the cylinder holes because of the recoil generated by the cartridge that is firing.

Without adequate crimp as others have suggested, the bullet will come forward and jam the revolver.  The cylinder will be unable to advance because of a proturding projectile.

Crimp is important with revolvers.

Good luck.

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Re: Roll crimp vs Taper Crimp for Revolver Loads

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