I know there aremany ways to waterproof the rear area of a sidelock (the nipple), but I just haven't found one better than my Kap Kover. The used to be in Cabelas, but guess they had a falling out. Here is a source to see what I am talking about, and buy one if you want:
http://www.octobercountry.com/products3.php?productid=539
The Hot shot nipple with an O-ring makes it work. The brass cover iseasy to put on, take off.It waterproofs and acts as a safety. You can put a primer on and pull the trigger and there is no way that the gun will fire with the cover in place. Pretty good if you ask me.
With the leather lanyard, you won't drop it in the words either.
Not bad for $11 !