PAUL

Hi, Cheers for the pics, I would say you gun is from the 80's, it's a S model as the pistol grip is the rounded type, as you provided a pic of the gun stripped down i can see it has the synthetic piston seal so this too would make me think the gun is from around the 80's as the earlier ones would have a leather seal ? not 100% on this as it is a point of upgrade for most tuners and i have done a couple of these myself to eek a little more power out of a low powered rifle. I'd bet it feels very long with a silencer attached

Your rifle here And here
PAUL