shifty said:
Are you talking about a Lyman GPR in 40 cal.
It's a 16" twist x .005 groove depth barrel made by Ed Rayl in West Virginia. From the barrel blank was made a die to engrave rifling on bullets to minimize the expansion needed to seal off the bore and prevent gas cutting, pretty much the same technique as used with the hexagonal bored Whitworth rifles. That lets you shoot heavy mechanically fitted bullets and bore size lubed lead bullets for target work, medium weight paper patched bullets for anything you're really mad at
and tightly patched round ball for small game out to 30-40 yards.
Too bad Indiana has regulations written around the unmentionables not discussed here and has a .45 minimum caliber for muzzleloaders, though not for the bullet diameter. Otherwise I would use the GPR for hunting deer.
In retrospect, without regard to deer hunting, the .40 could be improved for my purposes with a little slower twist. One turn in 28" would be plenty quick, load easier and clean up easier, and I suspect not be so picky in load development with bullets that don't look like pencils.
Could actually go even slower. The work ups I did years ago with a set of GM barrels 28" and a 38" in length showed me that though I could not obtain consistent results with lubed lead or paper patched in the 48" twist, it was right there on the cusp of being workable. I'd have the Eureka moment... and then flyers!
:redface:
So, I've kept the one GM 28" long barrel just for round ball. And I've given thought to having the 16" twist barrel rebored to .42 to paper patch with all those off the shelf .41 revolver molds. Maybe some day. For now I want to reach out and see how well yotes stand up to that medium weight 250 grainer.
Maybe some day the GPR will get rebored to a medium twist .48 so it will be Indiana legal and I can shoot round ball and paper patch the .476 revolver molds. Maybe some day.
But the last thing I'm going to do with muzzleloading is be in a hurry.
:wink: