That makes it sound like you cut your finger on the prop while pushing against compression, not from a backfire?

First, you should use a chicken stick or something besides your finger to avoid that kind of problem. (I guess you figured that part out on your own though).

Second, depending on the prop, I usually shave or sand off the mold flashing on the prop to make it more smooth and less likely to cut my fingers when doing simple things like priming and such.