a little tougher? heh, yeah, and .500S&W round's recoil is a little more stout than a .45acp's. They are tough as a non-polymer magazine can be. They are definitely heavy though. They have an odd finish on them though, almost feels like the beginning of steel oxidation. I like it though. I just bought two off that magazine group buy, and I'll be installing magpul followers today, so those kind of rig any reliability test. They work 100% thus far in my Bushmaster M4A3, with both wolf 62gr, and Remington .55gr UMC.
Hope this helps;
-James G.