An interesting observation with the new hammer extension from Uncle Mike's. They show installing them just like the H&R instructions show.
This time I'll opt to not follow directions...

FWIW, the size of the extensions shown in their instructions and also the review at Midway appears to be a heavier made product.

Actually, it is virtually identical to the hammer extension supplied with the Handi rifle, with the only difference being in the size of the mounting screw, which is a smaller OD than the H&R extension.
Bill