No offense but I really don't think you get what bump firing is. It is using the recoil of the rifle to move in relation to your stationary finger such that the rifle fires again upon return to its original position.
If you are "bump firing" with a 22 LR in a Marlin 60, I don't think you really are bump firing. You are moving your finger. If you aren't moving your finger, you've re-written the laws of physics.