16ga.com ~ View topic - roll crimp

Joined: 28 Jan 2007 Posts: 129 Location: hong kong

I have deceided to try some roll crimp loads. I have the BPI Multihulls, and my question is: Do I need to trim these hulls when loading 2 3/4 inch loads and using a roll crimp?

If triming is recommended, how much is left above the overshot card prior to rolling?

thanks, Ajax.

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan

You only want about 3/16" of hull above the O.S.C.
If your using a drill press, with plastic hulls, lube the tool and go slow. You don't want to melt or fuse the plastic together.

The total length of the shell before crimping should be the 2 3/4" measurement, same as in folded crimps. That's the length that has to fit in the gun chamber. Rolled crimps generally allow a little more shell length to be used for shot capacity than folded crimps do. But the length of either type of finished cartridge will be less than 2 3/4".

Guest

A 2 9/16th roll crimped shell has about the same internal capacity as a folded crimp 2 3/4 inch shell so unless you want to use a bunch of filler it is easier to trim your hulls to 2 9/16th inches. You can use the same loading data as you would for a 2 3/4 folded crimp shell but MV and chamber pressure will be a bit less due to reduced resistance from the rolled crimp when the shell is fired.

Joined: 28 Jan 2007 Posts: 129 Location: hong kong

thanks
Ajax

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan

Dave- Of course you're right; I expressed myself poorly I guess. Any length opened shell of 2 3/4" or less can be used in a 2 3/4" chamber. What I was trying to express was that the rolled-crimp shells did not need to be trimmed shorter than 2 3/4" (unless you want to make a shell that opens up shorter than this length) Thanks for keeping my words honest! Smile

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan

My only concern is that if you use your normal load, for a 2-3/4" fold crimped hull, and try to roll crimp it. You'll be trying to roll crimp about 3/8" of hull. You might get away with it on a paper hull, but I think it will be tough on a plastic hull. I hate roll crimping plastic hulls anyway. Paper works so much better.

Joined: 19 Feb 2008 Posts: 443

Dave Miles is correct. Just for fun I once loaded up some 3/4 ounce loads in 2" hulls and then roll-crimped them. You should have seen the looks I got at the gun club. Very Happy

sv

Member Joined: 02 Oct 2007 Posts: 1975

Steve,
What are you using for your 3/4oz load? I have some hulls that I am thinking about roll crimping. They were miistakes I made and I cut the hulls to get out the shot. They are BP hulls. I did not make the first cut to straigt, but there is enough left for 2 inches.

Guest

Joined: 19 Feb 2008 Posts: 443

I used a modification of my standard load. 15.5 gr of GD, some old BP plastic gas seals I had laying around, a cork filler wad, and an overshot card in a severely cut down Federal hull. They seemed close to my usual 1217 fps.

I sent some of them to Wisconsin & Steve Grozik killed a ruff and several woodcock with them using #8 shot. He saved the rest of them saying they were too cute to shoot.

sv

Member Joined: 17 Feb 2007 Posts: 497

Give some of those to Tiny, Steve Laughing

Joined: 19 Feb 2008 Posts: 443