I have two EARLY 700 carbines w/ 20" bbls and although slower powders give higher velocities, neither will shoot (group) worth a rip with IMR or H-4350 or 760 and various 130,150,165 or 180 gr bullets. With these powders,some groups are two inches plus. I tried H-4895 and IMR 4064 and bingo-less than an inch for multiple groups. Granted these are not at optimum velocities (3000 fps with the 130 T/shock and 2750 fps with the Hornady 165 FB), but I'm looking for accuracy and those loads are potent enough for deer.
All I can figure is that maybe the slower powders are producing higher muzzle pressure and it is disturbing the bullet base right at release. That's what I've found with my two carbines, your results may differ.
__________
NRA Life,Endowment,Patron or Benefactor since '72.
