I have not been satisfied with the accuracy I have been getting with cast bullets in my BC, so I broke the "one change at a time" rule this weekend.
I purchased some O rings about 10 months ago and didn't see much improvement, so I took one out of the cleaning kit and actually put it on the rifle.
I had been using 405gr flat nosed 20-1 bullets, I loaded Lazer cast 405's ( the 3 lube groove design) for this weekend. I took 4 loads, 32grns of IMR 3031, 25 grns of 5744, and 11 and 13 grns of Unique. These loads are all published in the One Caliber 45-70 booklet, but please check before using in your gun. I have been using a soft crimp, I went with a firm crimp this time.
Oddly enough, at 50 yds all these loads shot at the same place. I had a nice little group going between the 8 and 9 ring at 10:00. Because we were experiencing 30 mph winds at the range, I didn't bother adjusting the Williams target sight. I moved out to 100yds and had the same impact point. The bullets must have been on the way up at 50yds, and the way down at 100yds. the 11 grn Unique load shot about 1" lower than the others at 100 yds.
60 rounds later, I had a hardball sized hole at the 10:00 position, and all these loads seemed to perform OK. The 3031 and the 11 grns of Unique seemed to produce the tightest groups. I didn't measure any because of the wind ( the benchrest guy next to me had two of the little windmills out at 25 and 75 yds to check the wind, they both blew over). I'll try the two better loads next time I go out, and see what type of measured groups I get.
I'm not sure if it was the O ring, the hard crimp, or the lazercast bullets, but the combo really tightened up my groups.
Ed