Im going to be turning 21 next month, and im going to be purchasing my first handgun, a P99, i have already got my Illinois Foid card. Im wondering about the triggers i keep rreading about. for instance, what are the diff's between single, DOA and theres another one i cant think of right now. Also, what is the best ammo for self-defense in the 9mm, hydrashock? also, what are +p and + rounds? Thanks, ill prolly have more ?'s later.