45-90, still shoot 45-70?

[kevinsmith5]

I have heard several people say a 45-90 will still shoot 45-70 ammo. I'm curious as to whether anyone here has done it and what effect it has on the accuracy of the round in 45-70. I want to be able to shoot some of the heavier cast 500+ grain rounds in my BC, but the short throat won't let me. Getting the bore throated and having it run out to 45-90 will cost me the same, so I'm thinking of getting it taken to 45-90 if it won't hurt the 45-70 accuracy too much.

[Smokin Joe]

You can shoot .45-70's, the extra .3" of chamber will foul up and you'll have to clean it, but it works. If you handload, seating the .45-70 slug to a longer OAL will probably improve the accuracy in the 90 chamber.

[EsoxLucius]

Without seating bullets out towards 45-90 COAL you could damage the throat shooting regular length 45-70s.  The bullet could remain unsupported for up to .4" of its travel after firing where it could cant and engage the rifling at a slight angle.  Over time this would not be good for the throat.

[kevinsmith5]

I do hand load, so if I seat the bullets 0.3" less it will be OK? Or am I better off just getting the Linda Lovelace treatment and sticking to straight 45-70?

[kevinsmith5]

don't think a shallower seat would be safe unless I did something like use paper patch smooth sides.

[Ireload2]

You just use a bullet with a long bore riding nose and a short base section. That would permit longer seating with no modification.