If you live near a Dunham's sporting goods chain store they stock the Rossi hammer extensions and scope base, though the T/C base from Weaver fits perfectly. I'm thinking the last extension I bought from them was about $5.95. I've tried reworking one of the Uncle Mikes for the NEF and the Blackhawk with some success, but the final effort was not exactly confidence inspiring. The Rossi one needs to be mounted to the left so you can access the action release button on the right.