After finally getting the HW77k to behave nicely (tried several springs, piston seals, piston weights, and varied preload until I found a compination that works forme) the gun needs more weight up front.
Yes, I know that I should have got a 97k in the first place, but sometimes you have to work with what you got.
Are there any reasonably priced options for muzzle weights in the 77k?