Winchester Highwall 40-70 SS Chambering Problem

[John]

I have a original Highwall in 40-70 SS that I’m having a problem with. A sized case will not fit in the chamber. It binds with about 3/16 ish sticking out. Just using a sized case now, not loaded. I’ve lowered the die and am getting cam over. Cleaned chamber.

Brass - Bertram
Dies - Lyman for original chamber

Ideas? Thanks for your help.

[Don McDowell]

That Bertram brass might be to thick at the web.
If you can get ahold of a 30-40 Krag brass might see if it will drop in, then you could exand the case and fire form.

[Kurt]

John with out looking it up but I think the original .40-70 took something like a .403 or a .405 bullet. This would make the case neck tighter then the .40-70 now uses.

[John]

That Bertram brass might be to thick at the web.
If you can get ahold of a 30-40 Krag brass might see if it will drop in, then you could exand the case and fire form.

I found some Krag brass and it worked fine. Looks like it will be shorter than 2.5”. When forming does it stretch or does it need to be streched?

[Don McDowell]

It will stretch a little, but may need to still be stretched. But unless you're shooting patched bullets I don't think the little bit the case will be short to be a problem.
Buffalo Arms sells 30-40 brass formed to 40-70.

[bryany]

It will stretch a little, but may need to still be stretched. But unless you're shooting patched bullets I don't think the little bit the case will be short to be a problem.
Buffalo Arms sells 30-40 brass formed to 40-70.

Most of the 40-70 SS brass I have used required sizing of the bottom quarter of the case smaller than the FL die could do. I cut down a FL die so I could run the case all the way to the rim. That made them chamber just fine. Subsequent loadings have not needed this step.

I cut the bottom 1/8-1/4 inch off and then cut most of the top half off. A good machinist could probably make a sizing die but it was easier for me to ruin a FL die.

Bryan

[Don McDowell]

I'm just hoping this supply of JBA brass I have will work just fine whenever my 77 from Shiloh gets done. These rcbs dies I have size the brass down far enough they just flop right into the chamber on the hepburn.

[Randy Bohannon]

Redding dies over work my brass for the Shiloh 40-70,might be a good option for an original chamber,exspensive option for sure. RCBS seems perfect barely sizes fired brass.