OK I have spent years smoothing out airsporters. They are the best all round air rifle. Early models are the best.
Never use high powered springs, they reduce the power. Best to use standard spring & make an insert that acts as a sleeve between the spring & the piston housing. You can use beer can for this, just cut with scissors the aluminium sheet so that it fits inside the piston & wraps round the spring. Insert spring with graphite grease & assemble as normal. All the twang goes, gun shoots smoothly & if you are capaple of removing the piston front end washer spacer & re-asssemble without it ( this increases the swept volume ) you will have the best 11 ft/lb air rifle ever.
ALLWAYS USE BLUE TIN 5.6 WASPS for best power & smoothness.
