I've been playing with IMR Trail Boss powder lately, mostly in light loads, both CB and Jacketed bullets for the 8 X 57 Mauser, but I'd been using someone else's CB's for the 7.62X54R as well. I ran out of the ones I'd bought from other people, so started casting my own.
30-06guns asked me to provide my data on the 7.62X54R with Trail Boss as he's presently waiting on a couple of Mosins to arrive.
Monday, my Lee C185-312-1R mold arrived and after cleaning the oil off it, I fired up the relatively new casting pot. Made up 100 of them and since my scoped 91/30 Mosin has a real tight bore (slugs .3107), I used the lee .311 sizer and put gas checks on all 100. I loaded up fifty of them using IMR Trail Boss in varying loads. The boolits averaged 185-187 grains, so I made up some with 11.5, 12.0, 12.5, 13.0 and 14.0 grains of TB. Took 'em to the range this morning with the following results - 11.5 gr of TB gave me a 5 shot group of .855 inches at 50 yards, 12.0 gave me one a bit tighter at .502", 12.5 spread to .913" 13.0 stayed around .91 and 14.0 jumped to just over 1" at 50 yards. Looks like the 12.0 grain load for that bullet in my rifle is going to be the best one. Not wanting to take up too much bandwidth, I'm only posting the best target here. As usual, there's always one flyer that spreads the group a bit. No matter, I'm happy with it - Especially getting these results from the first boolits of my own casting that I've actually put downrange from one of my rifles.
Yup, I'm hooked!