.260ai
Im running a 260 ai, 22 inch bbl on a stiller tac 30 action. Mike rock 1 in 8 twist.
With 49.7 gr of 4831sc. (yup it's a compressed load) I am getting 2915fps, Norma brass, hydro formed with feud 210m primers. 139 gr lapuas. Absolute tack driver. The lapuas are the go tos, I have had .5 inch 5 shot groups at 300m. I have gongs at the farm, and are perfectly happy with under 3 inch groups at 600m. It likes the lapuas as well as the Berger 140 vids. Bergers it uses 50 gr of 4831sc. It's a chore to load, long tube on funnel etc but consistently shoots wells. The nut on the trigger end of the unit is the issue as I see it.
Love the lack of trimming, limited need to push the shoulders back. I have no issues dealing with the ai portion, in fact I have a .22 250 ai, 260 ai, and a 338 lapua improved. I hydro form all of them no issues and have limited brass working to do. My .338 brass has over 8 loads and have no issues, my 250 has 10. Good brass life
Just my 3 cents