Break it in with CCI minimags...about 500 rounds should get your springs/etc set right. Plus, they are really consistant in FPS out the muzzle.
Don't use HYPER-Velocity ammo UNLESS you put in a Tuffer Buffer...some folks also reccomend a higher poundage recoil spring.
Only use Remington rimfire ammo (Golden Bullsquish, Thunderduds, Viper-bit-me) when you want to experience lots of ammo-related failures.
Standard Velocity ammo (Target/Match) will give you the best precision, Wolf Match is decently priced, but dirty as heck. Clean after EVERY range outing...
Some brands of Standard Velo may not give enough recoil to work the bolt completely, causing Stovepipe FTE's...
High Velocity is the Norm...and the average choice for all sortsa stuff. Plinking Fun abounds!!
I'm not just Trigger Happy, I'm Trigger Ecstatic!!