Re: ammo from the box
Stealth,
I have a bushmaster varminter with a 1:9 twist and have been trying different ammo/reading reviews on the ammo and twist rates. Here is some info i have found
Depending on your barrel length and the temp outside the 1:9 twist should beable to handle up yo 75gr BTHP bullets (its about 50-50 i suppose, some will shoot them well, others not so much)
my rifle really likes HP's, doesnt like V-max too much and FMJ's arent too terribly bad! I plan to try some 68gr Match HP from Black hills in my rifle/barrel shortly, ive shot some Prvi 69gr that shot through the barrel, but it wasnt very conistent (thats what you get at $10 a box though) ive also shot some 62gr silver bear HP's with decent results!
i dont see how you can go wrong with Federal, hornady or Black hills!... personally i probably wont buy hornady v-max again as it was very dissappointing! i will probably stick with the 60+gr match bullets, or the lighter 50gr JHP
hope this helps in some way!