That little round plastic washer(?) on side of cocker...

[redroush00]

I fit the Gamo Cat action into the Hunter Sport stock and seems to work great...but...if i put the plactic washer on it , the action wouldnt sit down. Took it off and worked fine. Im not sure why because both actions appear to be identical and the washers appear to be the same. Why one worked with it and one without it is a mystery. Do i need this thing ?

[shadow]

Yes since it aid's in the smooth function of the cocking arm as it slides along the inside of the stock. You don't want the rod that the roller slide's onto to dig into the channel set up for the roller. The roller might be slightly bigger and you may need to do some fine sanding to reduce the diameter of the roller or make another from scratch. Ed