I can see the gasket may add a buffer when pumping if you hold the gun by the stock wrist but tbh on all my pumpers I hold by the receiver as by holding by the stock wrist it puts too much strain on that area of the stock especially on the 101's and the later 760's which are bolted there
I've got a sharps ace that has had to be repaired at the wrist and I bet it was because a previous owner was holding it there and probably over pumping it