I bought a half case of the Rio Royal 00 buck shells and they don't cycle at all on 1, fair on 2 and had to go to 3. (on the gasfixer plug)
I broke mine in on winchester super handicap and Winchester steel bb's both with a muzzle velocity over 1300 fps....I think closer to 1600 on the bb's. I would leave the wallmart stuff until it's broken in and always stay away from the winchester shells that wallmart sells.
How bout the Wally Winchester 00 Buck... I was gonna pick some up its a good price