I have been thinking about switching to the Mag #11's for the fact that they do fit tighter.
#11 Magnum Caps is all that I use, I tried the musket cap for several season both with the wings and without the wings.
Musket cap just had a couple of things that i really did not like. Often they would not stay on the nipple post unless you squeezed them which meant handling them and the othe fact I did not like are the the dang slits up the side of the cap.
With a #11 Mag cap installed on a good nipple and using a capper if you install the animal correctly you will never have to worry about the cap coming off, in fact you will have to pry it off unless you shoot it off, but it becomes nearly water proof by stretching the convolutions in the side of the cap - not water collecting slits...
This the nipple that i have found to get the tightest seal...

Here are a couple of other pics that might interest you...
This Ted Cash is the capper I prefer for hunting - it really compact and if you look at the tip you can see it has a piece of solid brass the the cap rests against when you are installing it on the post so you can relly push it on tight and stretch the convolutions in the wall of the #11 Mag... Make sure you get #11 mag caps or Dyniment Nobel !075+. They produce the same heat as does a Musket cap.

This is a picture of the various caps that i have used... You can see the slits in the both style Musket caps and the convolutions in the walls of the #11 caps.
