the same works for .458SOCOM.
That actually seems worthy of a new question. I'll even post a picture to spice things up.
My buddy just finished a .458 build, and so he's now using 30rd 5.56 mags as 10 round .458 mags. He was joking that if a ban goes through he's just going to claim them as such. The cartridge is specifically designed to fit in the standard mag for ease of use in the field, so I don't think they make specialized .458 mags. Also, a 10 round 5.56 mag would limit you to 3 rounds of .458.
So, the idea was that if he only used them for .458 they'd be perfectly fine even if there was a ban.
Does anyone know if that would work as an argument?