If you have a leak in your CO2 airgun you most likely have a damaged/aged seal (see picture 2), which you must replace. Just unscrew the slotted bronze nut-bush, which holds the seal in place, take out the damaged seal and replace it with the new one, then put back the nut. This seal has been redesigned and improved to last longer than the original. It has been tested and works fine with:

Crosman 1008, 1088, 357, 38t, 38c, C40, CB40, C41, 44 peacemaker, SA6, Crosman Auto air, Crosman 1981 Shiloh, Crosman Frontier 36, Crosman 1077 air rifle,

Umarex Smith and Wesson, Walther CP88, Walther CP99 (but not suitable for CP99 Compact), CP  Sport, Walther Nighthawk, Beretta 92FS, Beretta Extreme, Colt 1911, Desert Eagle, H&K P30, RWS Sig 225, Reck Police,

Gamo most models (but not for P23, R77 Combat).

Buy 2 seals and get the 3rd free!

Please, look at my 100% positive feedback and buy with confidence.