we cant give away all our secrets. but its not a stiffer spring and round after round after its quite dependable and accurate. we played with the stock hl gun and its a piece of junk. even with stiffer springs and tighter bbls it is just not reliable. from unsightly breach cracks to actually spitting out the rubber breach gasket,to the mentioned gear stripping they are just no good. the gun for us is one of the most important elements of the tank, if not the most important its got to be good.