As they say "old too soon, smart to late". This applies to my question here. In 1966 I built a 50 caliber half stock percussion Hawken, using a Bob Roller lock and Douglass barrel. W. L. Mowrey of Jacksboro, TX made the tang-breach plug assembly. It is a pretty rifle, inletted to perfection, using maple with nice striped figure. I elected to not use a hooked breach plug, although the two keys are in place as expected on a Hawken. But I made at least one big mistake. Not having an original Hawken handy, I went with a 1-1/8" octagon barrel. That barrel is 35 inches long. So the gun weighs 12 pounds! Too heavy. I don't know if Hawken made plains rifles with bores as large as 65 caliber. That would reduce the weight by 1.4 pounds. Can this barrel be re-bored and rifled to 65 caliber? I know that the breach plug thread will have to exceed 0.65". Does a re-rifled barrel require some shortening at the muzzle for best accuracy? If so, then the under-rib and two thimbles can be replaced, along with the dovetailed front sight. Shortening the barrel by 5" would reduce another 1.2 pounds of weight.