[DLeeO]

What does that infer 'blocked or pinned to 10 rounds'??? Why would you buy a 20 round mag that only holds 10? I don't get that.

I understand from the interweb that the "tall" 10 rnd mags, which look just like the 25s can be altered and made into 25's Some dude posted about it here in 2013, maybe '12? That's how I found this forum. Trying ANYTHING to get a few 25 rnd M&P15-22 mags. The 10 rnd conversion, though, seems sketchy or at least makes me able to break a perfectly running 10 rnd magazine.