Daystate MK3 FTR: not sure of name but a Daystate unit about 10cm long x 2cm diameter with carbon fibre pattern. Reduces noise to a very quiet 'phut'. Superb
AA S400: the Air Arms unit from when rifle was new ... many years ago. Very Good.
HW100: the HW one that came fitted to rifle. Very Good.
HW77k: the slip on HW one bought with rifle c 1985. Good
PAX Phoenix .177: Home made. Very good.
PH Dragon: dedicated PH unit, excellent.
SMK QB78 CO2 : home made for a bit of fun, very good.
All rifles are .177

I make a point of not shooting PCPs in the garden without a silencer. With springers it is not so important as the noise is mostly mechanical anyway. My HW77k unit acts, I think, more like a muzzle weight as it is completely empty anyway: more like an attractive tube.
Cheers, Phil: