If you look closely at the face of the hammer you will see a groove cut across the lower part. The lower edge of the hammer is sharpened to cut the tape off as the gun is fired.
A friend and I found a mint 42 and a mint 55 rifle behind a bureau in the attic of their house back in 56. I remember opening the tape priming door to see a mechanism that was identical to our cap guns.
You can still come across some of the original primer tapes at CW shows. I have two, one unopened and still in the original wrapper and the other opened. I have even seen some in the original cylinder container. I have an original M1855 Pistol Carbine and the mechanism still works.