Ill start out with a quick tale. took my Ruger #1 in 450 BM with the 1 in 10 twist out for deer and shot a nice 166lb manitoba white tail at 70 yards with the hornady factory 250. worked great no blood for the first 10 yards then a big bucket spill every 10 feet. Deer went about 30 to 40 yards , lungs were liquid.
now that the season is done for me I got to reloading. I used Lee 4 die set, starline brass, federal match SR primers, cfe blk, hornady xtp 300's and sst muzzleloader 300's.
groups are measured from edge of hole to furthest edge of hole, shot from a bipod at 100 yards in -2 degrees Celsius. I usually shoot from a bench while sighting in and I shot these groups pretty quick because I was laying in snow.
after seeing hoots range report I decided to start at 41.5 grains, this is higher than what Hodgdon states is max, there was some slight flattening of the primers but not bad. I cant say how the pressure will be in any other rifle than my own.
the SST seated to 2.300 3 shot , 0.4 inch group, average speed 1968 fps ( two shots through same hole)
the xtp seated to 2.055 3 shot group 0.7 inch group, average speed 1999 fps
was surprised the sst grouped about an inch and a bit lower than the xtp. Recoil was fine , I dont really notice it with the brake and wearing a coat but I also dont find my 338 win mag all that bad ether so take with that what you will.
I plan on trying 42 and 42.5 grain but am more than happy with this load