41 mag revolver, crimp?


August 16, 2010, 12:25 AM
I have been shooting some 41 magnum from a Model 657 Smith and Wesson. For the last couple of hundred, I have been using a slight taper crimp. A buddy of mine said this is a big no no. He said I must roll crimp these. If I don't is it a problem. So far so good, but am I pushing the envelope?

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Steve C
August 16, 2010, 01:01 AM
Depends upon how heavy your loads are. If you are loading full magnums you can get bullet pulling with the heavy recoil that can tie up your pistol when the bullet extends past the face of the cylinder. If you are shooting 1K fps or under LSWC's a lighter crimp shouldn't be a problem.

August 16, 2010, 06:59 AM
I always roll crimped my 41 mags just like I do my 44 mag and 357 mag. I almost always used H110, W296 & 2400, those powders need a good heavy roll crimp for consistent ignition.

Jimmy K

August 16, 2010, 07:26 AM
If the bullets are not creeping forward under recoil, you can get by. I always roll crimp .41 Mag when using close to or full loads. Helps the powder burn well too.

August 16, 2010, 12:02 PM
Almost all my .41 Magnum loads are what I would call full power, so I crimp them all. It also helps to get complete powder burn and make the round more efficient.

Hope this helps.


August 16, 2010, 12:25 PM
I've been reloading nothing but 210 gr cast with 7grs of Unique for years with a slight roll crimp.

If I was reloading a heavier load I would increase the roll crimp.

August 16, 2010, 12:26 PM
I gotta ask where you got a .41 Mag die that taper crimps.

I didn't know anyone even made a .41 mag revolver die that doesn't do a roll crimp.
Thats what revolver bullets are designed for.

At any rate, you roll crimp for revolvers, and you taper crimp for auto-pistols.


Bush Pilot
August 17, 2010, 01:18 AM
+1 to everything RCMODEL posted. I use a roll crimp on all .41 mag loads.

August 17, 2010, 07:45 PM
This is a Lyman 3 die (carbide) set. I have f-d around with it to try and get a roll crimp to no avail. Maybe I am just overlooking something. I will dig through all the papers again and see what I am missing. Thanks

August 17, 2010, 08:36 PM
I have used those dies and they will roll crimp if properly adjusted BUT: there was another thread recently about some guy who bought a set and had a problem because they placed the wrong die in the set at the factory. So we need to rule that out first. Are you attempting to seat and crimp in one operation? I seat the bullets first and then back the seating plug back out and then screw the die down until it starts applying a crimp and then crimp all the cartridges. Trying to prevent bullets pulling under recoil by using heavy crimps is a waste of time. The crimp does almost nothing to hold the bullet in the case. The neck tension is what holds the bullet in place. If the expander plug is not at least 3 or 4 thous. under bullet dia. it is over expanding the case mouth and the bullets will not stay in place. If you seat a bullet (with no crimp applied) and press it hard against the edge of your bench you should not be able to push it deeper into the case. Any at all. If you can move it, you need more case neck tension. If you cannot move it the bullet will not pull under recoil. The expander plug can be turned down in a drill press until it is the correct size. Once you achieve sufficient case neck tension crimping only serves to remove the flare you put in the case and leave a light crimp. Using heavy roll crimps will only work harden the case mouth and cause it to split. When you seat a bullet you should be able to clearly see the outline of the bullet and where its base is just by looking at the cartridge. I didn't make this up, this is how Elmer Keith explained it in his book. And he was right. I have been reloading .41 Mag ammo with heavy bullets and heavy charges of 2400 for twenty years and I have never had a bullet pull and I am still using brass from 1987.

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