aftermarket parts

I cannot find anywhere that really tells me what after market parts do on snipers. I have heard of "Zero Triggers" and I sort of understand what a hop up is. I am new to sniping in air soft and I have little knowledge of internals. Can anyone explain this to me. I use a Bar-10 JG Full Metal...

I'm just curious, but has anyone bothered to make any aftermarket stocks for some of our sniper rifles? I toyed around looking for them for a few minutes and didn't find anything, but I for one would love to have an aluminum stock of some sort. I'm rather disappointed with the bipod mounts on my...