I use 8 of the Thermold 20's, the only problem I have is with my Maglula loader, I have to hold it on a little tighter. I use them more than any other mags that I have. I have yet to have a failure with one, of any kind. I had read reviews on the 30's so when a kid offered to buy them from me, I sold them but he is still using them and they havent given him any problems. I have never bought any of the 10's so I do not know, but the 20's have worked like a charm for me, in my rifles or in friends and families rifles of many brands. I will still recommend them. I also have some TangoDown mags that I got for a good price. I have 11 of them right now I have 5 in my regular rotation. Not a single problem with any of them. I do not know what I do differently than other people but I dont have mag problems, no broken feed lips, no feeding problems, no issues. So I in good faith can recommend both of these brands of mags. I do have the original Pmag that came with my rifle, I have used it a couple of times and has given me no problems either.