Hepburn .40 1 7/8 chamber specs needed

[Spud]

I have a Remington No.3 Hepburn marked .40 1 7/8 under the barrel (.40-50 SS) however a chamber cast revealed a chamber 2.8" long at which point the rifling starts. Rate of twist is 1 in 20". Is this standard for the .40-50SS? I can also chamber a loaded .40-70 SS cartridge in this rifle. Everything looks factory standard with no sign of a recut chamber. What have I got here... a standard .40-50 SS or a .40-70 SS with an incorrectly marked barrel? Has anyone done a chamber cast of either of these calibres. I'd be interested in the details. Thanks
Spud

[Tony Kastella]

Hello, I had a lot of trouble trying to figure out my chamber and caliber on my Remington Rolling Block. I have the 40-70 Remington Bottleneck and this is very different from the 40-70 Sharps Bottleneck. I found the book "Shooting Buffalo Rifles of the Old West" by Mike Venturino to be very helpful in a lot of ways about caliber and lengths and such.
I sent a chamber cast to CH Tool and Die (Mt. Vernon, Ohio) and they had a neck sizing die sitting on the shelf. They were very helpful in a lot of ways including determining the groove diameter and thus a bullet diameter.) 0.409"
My biggest problen was findig cases, which i use 45-90 straight and trim back, and powder, Goex or Swiss not much in either line in the Portland Oregon area.
Buffalo Arms of Idaho has a lot of supplies of you still need them. others do to as well. Good luck! Make it into a shooter! Tony K