chamber cast

[hendrick]

Anybody with an original 56/50 carbine ever cast and measure their chamber. I have my M1865 original src and would like to know just how much variation there is in different chambers for the same caliber.

[Arizona Trooper]

I did a sulphur cast of my '60 rifle several years ago. Bobby Hoyt made his chamber reamer from it but I don't recall the exact measurements. I do know that there is quite a lot of variation in the groove diameter of the bores. I have slugged them from .534" to .540"  Also, the groove diameter of every rifle I have slugged (5 or 6 of them) tapers .003" in depth from breech to muzzle. It's interesting that Spencer let the groove diameter vary so much, but kept the taper the same.