A couple of months ago I bought a HW50 at auction, it's an accurate, punchy little rifle, and by and large I'm pleased with it. The only fly in the ointment was that it was running a "little" bit hot. When ever I picked it up to shoot, the first shot would diesel heavilly, the second shot would go supersonic (yes, with a proper crack) and then it would settle down and shoot properly from either the third or fourth shot.
Today I fired up the old You tube and watched a strip down guide, and then took mine apart. Other than the 4 little square tiles, it all came apart very easilly. Inside, it was just slathered in grease; plenty of detonation fuel there then! I cleaned off all the old stuff from the piston seal and mainspring, and swabbed out the cylinder before sparingly re-lubing it with some fresh LT2 grease on the mainspring and piston skirt.
It all went back together fairly easilly, other than those fiddly shims in the breech jaws, and now it's shooting sweet as a nut.
I wish I'd not discovered Weihrauchs to be honest, as I'm now in two minds whether or not to sell all my Webleys