I recently purchased a New England Firearms Model B2 in 308 caliber from a local pawn shop. The rifle looks like new or has been little used. Problem! Cant get it to shoot.  It only fired one round out of a box of new factory ammo. Primers are slightly dented.  I replaced the hammer spring with a Wolf Spring.  No change.  I tried reloading with primers set at different depths.  Tried Federal, Winchester and CCI primers.  The Federals fired several times, but nothing I would take to the woods and rely on.  Any suggestions on what the problem may be?