A:Answer Miller-Coors uses a few styles of kegs, one of them is wider than a “standard” 15.5 gallon keg, so the door simply doesn’t close. If you look at the picture I included, the one on the left is too wide, the one on the right works just fine. Blue moon is made by them, so you might run into the same problem if you try to get a 1/2 bbl from them, so just keep it in mind when you buy a keg, they have either style of keg available generally