easy to "spot" ( and measure as well) the 5 1/2 inch bulll barrels are just that, BULL BARRELS, no taper to them, the 5 1/4 inch has a taper out to the front....measure from the face of the bolt to the end of the barrel from the inside,bore...OR from the front edge of the ejection port, to the end of the barrel......last we knew there were like 1400 of the T-514, maybe Chad can "update" or give a better count...............bottom line ,still a very fine and hard to get 22 semi auto............