HR, I plan to use the rifle as a combination deer, coyote rifle. In the past as a 243 it was used as a deer rifle with 100 gr bullets. I wanted to use 85 gr bullets at 3100fps which was possible but at high pressures. I had the rifle rechambered to 243AI and now 3100fps is easily within normal pressures. I started hitting high pressure signs with most powders tested at around 3200fps. A few powders didn't show high pressure signs at all at 3200fps. The powders I tested were 748,N140,N150,N160,H414,H380,H4350,Re19,Re15,H4831 SC. I accuracy tested most of Hodgdon powders at 3000fps earlier and 748 was the most accurate. This rifle as a 243 and 243ai has always favored faster burning powders. With 100 gr bullets, it printed one hole groups with IMR3031. As an ai, at 3000fps, it printed 1/4" groups with 748 and 3/8" groups with H380. I was looking for the upper limit for pressures in my rifle. Now I'll accuracy test the loads and see what it likes. I was wrong about the twist of my barrel, it is 1-10". I was thinking of the 1-9 of my 280ai.
Russ,
Are you sure about those velocities? The loading manuals I have here show that charge weight producing 3400fps with that bullet weight. I got very erratic results with 414 in my rifle. Large velocity variations with it. The highest velocity I was able to get 3401fps with 48.3 gr of 414 but that really flattened the primer but then you are using very light bullets.