The 38-56 is about .375 caliber although groove diameters may run a little larger. It is a black powder round. Cases can be made by necking down 45-70 brass. 1886's in 38-56 are usually in the lower price range for 1886's. A fairly rough one sold at auction here a couple months ago for about $1300. The rifle was solid but the wood was battered and the bluing had all gone brown.
