Great post - Everyone should read!
I have a question if anyone knows the field I play at does not allow plpugs, they say it is possible for the plug to be launched and hurt someone, it seems reasonable to me but I have never tried to experiment as I'd prefer not to have to clean out my marker. If this is true it would make sense that almost everyone would adopt the barrrel cover (of course i have seen barrel cover just loosely placed over a barrel and not secured which defeated the purpose). Anyway I have always wondered this as different fields allow different things.
BTW - I plan to request my field to add a few of these to their safety briefing.