The bullet that killed Lincoln

[L Verge]

Booth was known to have been a good marksman from an early age, I believe. There are mentions of him visiting shooting galleries, and we have also heard family stories from people descended from residents of the H Street neighborhood near the Surratt boardinghouse that Booth was supposedly known to take target practice in the backyard of the boardinghouse.

I guess no weapon is a sure shot (just ask Powell about his experience in the Sewards' hallway), but evidently Booth felt confident of both his ability and the derringer's to do bodily harm.