Having discovered several of the camps that the 9th Battn MO Sharpshooters occupied in Arkansas, I can tell you that the vast majority of bullets recovered were 0.577 and 0.54 cal Enfields, primarily the type known by bullet collectors as the "Marshall Texas" pattern Enfields. Others also recovered are known as "2-ring Mississippis", but this is simply a regional moniker for the bullet.