Hiya Cerwyn,
As it happens i have the old spec.ppsh so here are a few pics to show you the bypass set up.You will also have to have the open chamber and barrel for it to work .
Have a look and see what you think
looking from the underside at the bypass steel plate

with the barrel and shroud removed

with the bypass plate removed

and the open barrel

I hope this helps mate
Kickback
