I have the HW80 in .20 and had it from new in 1997.
Tuned by Venom with a Lazaglide action and moderator and a GinB stock it's pure magic to shoot.
It's a great air rifle and has accounted for many rabbits, crows, magpies, pigeons, jays and squirrels.
I don't think I'd go to any other calibre.
Best pellet I found were the Bisley Super Fields at 11.42gn but now they've stopped being made I'll have to look around for something else.

Ed