On the Cooey shotguns fore ends there are 2 different spring locking mechanisms one has a leaf spring and fits the older style of gun possibly the Cooey before Winchester and the second has a coil spring and is for the later Winchester Cooey shotguns. I don't know if there is any overlap where a leaf spring will work in a Winchester Cooey gun. Also if you are not able to get the proper one for the gauge you have , the barrel channel can be opened up to fit larger gauges, so a 20 or 16 gauge wood can be made to fit a 12 gauge.