if anyone isn't sure what one of these looks like, here's one on my hw35, the push onto the barrel then lock in place by tightening the smaller bit with the nut shaped bit with a spanner...
>>>webley pro system silencer<<<
only posting this as mine was on the rifle when i bought it, had no idea what type it was until someone described it on here
bump it up there!!!!
regards, john
ps, sorry i don't have a closer pic....