Not much to do today so got the old Tenma sound level meter out in the garden. The measurements were taken 1½ feet up and 4 feet from the meter to the muzzle. dB peak-hold and A-weighted.

Scorpion pistol ~5.3 FtLb .22
101.5 100.4
With cocking aid 104.5 104.5

HW45 ~4.9 FtLb. Sold as a .22 but fitted with a Weihrauch .177 barrel.
105.8 105.9

HW80 ~10 FtLb .177
106.8 107.0

Beeman P17 ~2.2 FtLb Single pump pneumatic .177
100.4 100.9 102.3

Surprised that the Scorpion's cocking aid makes the gun significantly louder.