45/70 Crimp Required?

[ruger1228]

When reloading a 45/70 case with 405gr LRNFP is a tapered crimp required?
Thanks for any help you can provide.
thom

 

[rcmodel]

If it's for a lever-action tube magazine, a heavy Roll-Crimp is very much required.

If it's for a single-shot rifle, just a light taper-crimp or roll-crimp, or even no crimp at all is O.K..

rc

 

[flashhole]

In a 45-70 (at least my 45-70 Marlin Guide Gun) the type of crimp can make a significant difference in accuracy. I switched from a roll crimp to a snug taper crimp years ago. No problems in the tubular magazine and my loads are pretty stout. I shoot the Hornady 350 grain RN bullets over a healthy charge of H-4895. The caps in the pic below were 100 yards out. I could not do this with roll crimp ammo. Can you guess which ones were the 45-70?

This link may be of some help.

http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/49

 

[rcmodel]

A "healthy dose" of H-4895 fills the case, supports the bullet base, and bullet set-back from recoil and spring tension in the magazine tube is impossible.

However, if you use less then a healthy dose of a different powder?
That doesn't fill the case and support the bullet base, a heavy roll-crimp is required.

rc