Hi
Lots of different grips and forearms, both factory and after market. The G2 grips do not fit the Contender nor Contender on the G2. To switch from rim fire to center fire. Look at the hammer. Some, if you look at the front/ striking area, there are two halves one that sticks out a bit. There is a slot for a screw driver...The half that sticks out, up is rim fire, that part turned down it is center fire. Enjoy and welcome to the addiction...So many barrels and so little time!
jim