To be clear, as some seem obsessed with the lock, which is not why I am asking this. I made, have, and use a cow's knee. I even posted pics. I do seal the pan, and, I do not invite moisture into the pan once it has been primed dry, by opening it while it is raining or snowing/sleeting. Opening the pan repeatedly during precipitation seems counterproductive. Between the cow's knee, the sealer around the edge, and now, keeping my bag, horn, and lock, under my match coat,,,, I have no issue keeping the lock dry.
I am simply trying to cover my bases for when I can not always keep the muzzle pointed downwards.
I've used condoms and tape on modern guns, does not seem appropriate when everything else is pc/hc when hunting with my flintlock.
Also, why buy something I can so easily make?