I have 2 sets of aluminum slot mags that I am wondering if any of you guys can help me identify. I have a guess who the Mfg. of the narrow set is, but have no idea who the big ones are made by. They look 50's with the wide lips, but have the small lip on the front side edge so maybe 60's? The first set is a pair of 15" x 3 1/2" That have the initals R.W.I. on the back, made in the USA, and the size all cast in. The second set is a pair of 16" x 8 1/2" aluminum slot mags, there is a number on each flange on the backside one has 534 9A20 on it, and the other has 521 8K08 on it in the same place, which I am suspecting is either a number in the run, or date code.. I have included pictures to help sort my questions out, thanks for all of the help!