I just picked up a 9mm carbine that had a broke firing pin and the ATI stock already on it. I haven't been out to shoot it yet as i just received the firing pin. One thing that I noticed is that it takes an extreme amount of force to pull the charging handle all the way back. The last 1/2 inch of travel is extremely stiff and I can hardly get the charging handle to lock into the enlarged opening in the dust cover. When I cycle the gun with an empty mag the bolt doesn't seem to clear the back of the mag to pick up a round with out having to put a large amount of pressure the last 1/2 inch or so. Is this normal for these guns or is there something going on?