Did some testing and ammo workups with the BCL Bison. This one has the 1-7" twist and the BCL folks suggested heavier bullets work the best. I had some 55gr, 69gr, and 77gr factory ammo to test with, and some 55gr Hornady to reload with. I then got some 69gr and 77gr Sierra Match King HPBT to reload with. Definitely it's liking the 77gr best so far. Test fired and chrono'd at 50y, and did a quick test at 100y.
initial 50y testing of PMC 55gr, Sig 77gr, 69gr Federal Gold Medal Match, and Hornady 55gr FMJ with H335 load workups
50y testing with 77gr & 69gr Sierra Match King HPBT and H335 Workups
A quick 100y test. Will do more of this and 200y testing now that I have my loads narrowed down. I'm using front & rear sand bags, but the variable is still probably me lol. I did turn the stock Triggertech trigger down to 3lbs.
Tried some lower speed 55gr 5744 loads to see if the lower speed would help the 55gr Hornady group better. It does help, but still not great at 50y
My chrono data
Overall thoughts on the Bison so far is it's a great rifle for bench shooting. Can be very accurate with the 77gr bullets. I have some 90gr bullets I'll do some load workups with, but that will take a single shot sled adapter as the reloads would be too long for a magazine.