The problem is that Weihrauch pistons are very soft , one cure is to fit a V-Mach V-Glide kit . If you dont want to spend that much rebuild it putting Rocol dry moly paste on the rear of the piston . Rub a light film of moly grease to the side of the piston seal enter it into the cylinder , then rub Rocol onto the rear of the piston push it fully into the cylinder and then rub some onto the wall of the cylinder behind the piston.
.22 Venom Mach 1 (FAC) 6-25x56 Millett.
.22 Venom Mach 2 Thumbhole 6.5-20x40 Leupold EFR.
.22 Venom Mach 2 Sporter 4-12x40 Leupold.
.177 Venom Vantage 4-16x50.
.177 Venom Daystate 8-32x56 AGS.
.22 Venom Datstate 4-16x56 AGS.
.22 Webley Venom FX2000 6-18x40 Busnel Legend.
.177 Titan MPT by Steve Pope 6-24x40 Tasco.
.177 Pro-Sport 4-16x50.
.22 Webley FX2000 3-9x33 Leupold EFR.
.177 Logan Solo 4-16x50.
.22 HW90 (spring powered) 4-16x50
.22 Gamo Stutzen.
.177 Walther lever action.