I just obtained a like new Mod 10 .223 Rem. It is a real tack driver. The problem I am experiencing is that about every or so often I get a failure to fire. The trigger feels like it fires and then stops halfway as if the Accutrigger has stopped it. When this happens, the trigger is stiff and will not move at all with a round in the chamber. If I lift the bolt to recock it, it will fire normally. I once had a problem with too much oil in firing pin galley doing this, but that is not true here. Any thoughts on problem and fix?