Have a little short barreled TC Black Diamond. Have been thinking about making a breech cover for it to keep the 209 primer from possibly getting wet. The Black Diamonds bolt lays back from the primer and when the trigger is pulled it slides forward (heavy spring) with much force and smacks the primer with a small detent. And if everything was done right it goes...BOOM. So the primer stays exposed to the elements when the gun is in the cocked position. This is definitely a gun that you would have to hold under your poncho on the stand in a rain storm. Just have not came to a conclusion on what material the make the cover out of. I think that you would definitely want to take it off before firing. Therefore I would want a fastener that is easy to access with gloved fingers and does not make any noise. Could probably treat a piece of deer hide with some snow seal and keep the elements out for a while. Just don't know what kind of fastener to use. Velcro is much too noisy for hunting. But then again, if it is raining on a leaf covered forest floor it may be all the camoflage you need! Too many ifs.