Impressively quiet with the new HW silencer. The action itself is quieter than everything but a Daystate MK3. The magazine, single shot adaptor and trigger are very impressive. But for all that I still wouldn't buy one, especially in the standard issue. I'm just not keen on the stock or the removeable cylinder. That said if you get one fitted with an Air Arms cylinder (with quickfill) and plonk it in one of Paul Wilsons stocks you have a stonking rifle.
The problem with all that is that a 500 quid gun has just mutated into a 900 quid gun.