If you don't want rain or obstructions in your barrel...
If you don't want rain or obstructions to get in your barrel while you are hunting, take a small piece of electric tape and put it on the muzzle of your rifle.
I tried it 2 years ago here in the rain forest (WA state), and I actually shot a deer with it raining, and the tape on, the pressure just blows the tape off. You don't have to worry about water, or leaves, twigs, or whatever especially when you are walking through extremely thick brush (in WA state).