Sick Drummer Magazine

Hey everyone, I have an Alesis DM-5 and have been using it for about a year now, but there is something I haven't been able to figure out. I play extreme stuff with gravity blasts and the problem is I can only use a few different snare samples for it, if not it doesn't register all of the hits. I've tried lowering the decay but it doesn't help. Shouldn't each sample triggered cancel out the last one allowing for unlimited speed? I would like to use a snare sample with a bit more of a twangy/rimshot type sound but it doesn't work for the gravity blasts. Any suggestions as to how I can fix the problem?