I filed the front sight down by calculation. The first shot of the day settled the barrel back to the breech, top left. These are .490 Hornady balls and 50 grains of Goex 2F. No wiping and no cleaning patch on the seater jag. This barrel was a reject from the GRRW. I cut an inch off the muzzle and 5 inches off the breech to eliminate most of the rifling chatter on the lands, but there is still chatter 4 3/4 inches forward of the breech. I lapped the bore with a hickory dowel on a cleaning rod and 240 grit Brownells lapping compound, but could not eliminate all the chatter. So I wanted to see if it would shoot with those rough lands. No wiping or cleaning for all 16 shots, and the balls still loaded easily and shot well. The bottom number 4 was really the sixth shot.
Middle target was the same except Goex 3F. The low shot was caused by a patch too small to cover the ball.
The right target was the same components except the powder was Olde Eynsford 2F measured with an 80 grain Goex 3F measure, which held 84 grains of OE 2F. (Couldn't find the right measure). The .010 patch was too thin, 3 of the 5 blew. But I was too cold to keep shooting.
This salvaged Green River barrel I believe will shoot as well as or even better than most barrels I've built with thus far.
Now, on to the next one(s)!
gusd, thanks. (He is referring to my article "A Utah Pronghorn Hunt" in the Nov-Dec Muzzleloader Magazine, the current issue).