Not trying to suggest anyone do as I do...just wanted to explain another viewpoint about "transporting loaded MLs".
Before I leave for a hunt, I prep then load my Flintlock in the garage...I then lay a 1/2" strip of thick military OD no-residue masking tape across the pan, up over the vent & breechplug, and close the frizzen on it...then I cover the muzzle as well.
Two benefits:
1) There is no way for any moisture to get into the bore;
2) There is no way for an ignition source to get inside the bore;
Get to my location, peel off the tape and stick it on the stock opposite the lock;
For the trip home, dump the prime, peel off the tape, and secure the vent again;
Get home, pull the ball, pull the tape, blow out the powder, patch the bore.
Unless I'm overlooking something, I think that's pretty darn safe.