Every rifle shoots commercial ammo a little differently. In fact I just got done reading a thread where a guy claimed that his Bushmaster gets better accuracy than Q3131A. My experience is completely different. Wolf shoots 4 MOA in my gun at best.
It all depends on the RRA Varminter's chamber. If it is chambered for SAAMI .223 REM (for higher accuracy) then I would not recommend any 5.56mm.
[b]I would not recommend:[/b]
LC XX (any year) (5.56mm)
Win. Q3131(A) (5.56mm)
SA Battlepacks (5.56mm)
Guatemalean Surplus (5.56mm)
S&B (any)
Wolf (.223)
Someone elses reloads (any)
[b]I WOULD recommend:[/b]
Remington UMC .223
PMP (gazelle box) (.223)
Winchester USA .223
Black Hills (.223)
Remington or Winchester game loads (.223)
Your own reloads (.223)
[b]I have had best results with:[/b]
Winchester USA 45 gr. JHP (commercial hunting ammo)
PMP (gazelle box) for plinking.
[b]I have no experience with:[/b]
Olympic ammo (Greek 5.56)
PMC (any)
Hot-Shot (.223)
Coyote Duster (.223)
Silver Bear (.223 I think)
Barnaul (.223 I think)
Malaysian Surplus (5.56mm)
Radway Green (British 5.56mm)
Hornady TAP (.223)
If your chamber is 5.56 and your bore is chrome, shoot whatever you want. Otherwise, take care of that weapon, and shoot good ammo.