I have 24 brit grey mags with the new magpul followers in half green in the others with wolf X power springs and they are the toughest most reliable mags I have in my inventory.I happen to have gotten mags that didint have catch hole dimension problems.I recently went through 500 rounds out of those mags and they had been loaded 6 months and they were flawless.If you get good ones they are the best.Just buy them local so you can try the mags in your rifle before buying as what I did.My dealer had a huge box filled with them and the first 24 I pulled out clicked in just fine with minimal effort like an aluminum mag.The biggest advantage the steel have over the aluminum is longer service life and wont bulldge over time from use or being loaded long periods,its undisptedly tougher and with good internal components in my opinion un equaled in stregnth,durability and reliability.If you get them cheap like I did the upgraded internals only bosst the price of the mag a couple dollars more than a labelle teflon mag with I also have and they are great.I just like having the most durable mag as in evevry thing I have ever read about the M16 is that the aluminum mag is the weak link in the system...try em and then buy em..with out hesitation.And as far as rusting like alot of people will bring up,traet them like any steel surface wich an AR has plenty of and they will be fine just like my AK,M14 and others.