Roll crimp vs taper crimp... about 25 fps

[westczek]

I've been working up a load for my new to me S&W 627 in 38 Super... umm working down a load actually. I thought I would use the same load I was using in 38 Short Colt for my 686s. However, I am using it for Steel Challenge, so no need to meet USPSA minor power factor. I figured the extra case capacity would mean a less velocity. I used a roll crimp. That gave me about 900 fps with a 158 grn poly-coated bullet. Then I tried a tapper crimp, about 875 fps. Change one thing at a time... have some idea what it does.

Westczek

[RevolverJockey]

This may not be the place to ask this question, but lately I have become concerned about roll chrimp. Some calibers don't come as roll crimp - 40 comes to mind. I have not had any retention problems yet, but I do use range brass exclusively. Is the a solution for these typically auto calibers?

Lee

[westczek]

There are people more experienced than I on this forum, but I'll take a stab at this one. You can roll crimp auto cartridges for revolvers, because they are headspaced off the moonclip, not the casemouth. I generally don't roll crimp, because I want my brass to last as long as possible. Repeated roll cripping can lead to splits in the casemouth. The benefits to the rollcrimp are that it retains the bullet better under heavy recoil and allows pressure to build better before the bullet is released, giving higher velocity.

Westczek