OP, I wish you very good look with your attempts. I own and have owned a number of hunting rifles - and have taken many dozens head of various big game. Most of my big game centre fire hunting rifles would struggle to do 5 shot sandbag rested groups at 100 yards, of 1.5 inches or less. So that is a really ambitious goal, I think. I have two - a 9.3x62 with 250 Accubonds, and a 338 Win Mag with 225 Accubonds, both bolt actions, that I have done a reasonable amount of tuning on - each of them will do 3 shot groups, from sandbags, under 1" at 100 yards, almost every time I try. But even with them, it is a "not always" deal. Just happens often enough, that I don't do any more fussing with them. For hunting, mostly the cold barrel shot that is the "money maker", and those seem to be dependably "good".
I have just pretty much finished up assembling a CG63 in 6.5x55, and two 7.62 NATO rifles - time to learn how to go longer - so have found a 300 yard shooting place - going to be working with those rifles, at that range. All new for me - do not know if I still have the eyes for the aperture sights on the PALMA style rifle, but will try it. The other two have 12 power scopes, so not too worried about "vision" for those two - at least for now...
