Allot would depend on how the targets were layed out ,
i dont think its only about capacity.
You may start infront of one target and then have nothing to do for 10 steps before engaging another two etc, after that first one i am reloading.
I think the question is slightly contradictory,if we are going to assume no misses for the purpose of this excercise then we cant assume that we might miss a shot or two.
I do think i understand though and would say that it would be better not to shoot to slide lock.
I still think it all depends on where the targets are placed..