question about ammo

bentbolt308

Sergeant
Full Member
Minuteman
Oct 19, 2011
519
13
s.e. iowa
i usally shoot a-max 168gr 308. and recently bought american eagle cheap ammo just to shoot and nothing more. both times i went out to the range with my gun it shot high 3-4 inches for the first 2 shots then came down to where i was aiming. this happened both times i shot this ammo with a cold gun and never had a problem with my a-max ammo. what could cause this. sorry im new to rifle shooting.