I bought a new Ruger MKII standard 6" a few years back. It also had a tendency to stovepipe. Pulling back its bolt with the hammer down required more force than other MKIIs I had fired. It seemed like the recoilspring and mainspring needed to be "broken in". For the first several hundred rounds I fired only "hot" ammo (CCI stinger and CCI mini-mag). This ammo functioned fine (I used this ammo because it was available at a nearby store). I stored my MKII when not in use with the bolt locked back, to compress the springs as much as possible (I have no proof this works, it just seemed that it wouldn't hurt). About a month later (after 500-600 rounds), it was reliable.
Hang in there, and shoot it a lot.