Howdy Pard,
You need to check the State codes in your home state regarding specs required for powder storeage. (they vary a bit from place to place) As a generality the powder magazines sold by Dixie Gun Works will pass most any regs concerning powder storeage.
Requirements in my state are that a Powder Mag must be moveable, have a locking device, a non sparking liner, and a given "burst pressure strength" (which I cain't recall off the top of my head). I cut the cord off an old refridgerator and put a hasp on it for locking, and got it approved by the Fire Marshal as a storeage device!