Between the Frame Bridge in the valley of the Dustcover, and the Recoil Spring/Guiderod assembly. It is suppose to "Dampen" the shock.
The Compact may not have enough room to run one... There are some that are thinner than the majority of the ones out there like the Wilson's. That may be the choice you need to consider.
Personally, I avoid them. Just another thing to cause the gun to choke. Even with proper maintenance, you will probably find that you're changing them every 200-300 rounds, for me, that could be a range session. Some have run them more than 500 rounds, and the buffer shows no sign's of wear, and not cut's, but in a tight/short action(stroke) gun, that may not always be the case... YMMV...
The Compact may not have enough room to run one... There are some that are thinner than the majority of the ones out there like the Wilson's. That may be the choice you need to consider.
Personally, I avoid them. Just another thing to cause the gun to choke. Even with proper maintenance, you will probably find that you're changing them every 200-300 rounds, for me, that could be a range session. Some have run them more than 500 rounds, and the buffer shows no sign's of wear, and not cut's, but in a tight/short action(stroke) gun, that may not always be the case... YMMV...