I personally have a slight feeling it's the mag... Can see on the top of the mag where the bolt is sliding across it,.. And now after shooting it more, the gun does seem to be feeding more reliably.. I'm wondering if the bolt was rubbing on the top of the mag and causing too much friction and slowing the bolt down... I'm not fully convinced but it's a theory.. I'm getting consistent 1.5 - 2" 10 round groups with the A17 rifle now with federal blue box and the cci a17 ammo, regularly shooting groups under the 1.5" mark but not enough to call it consistent.. I'm happy with the gun, but I only need 1 so when the second 1 arrives (this week hopefully) it will be going into the EE..