Fotis,
IMHO, your buddy needs to send that rifle back to Ruger.
I have the 22lr Compact and it shoots really well, particularly with CCI 40gr Standard Velocity RN.
Mine wears a fixed 8x Leupold and I have fired 3/8" groups at 50 yds and ~1 1/4" group at 100 yds.
See the comments here;
LINK Ed