PDWs...and other small arms.

[stanc]

I wonder how well a P90 style magazine would adapt to the Grendel cartridge?

My first thought was that it probably wouldn't work. IIRC, the 5.7 FN cartridge case has no taper, making it emminently suitable for a long, straight magazine. In contrast, the 6.5 Grendel case has noticeable taper, which would seem to require a curved magazine for capacities greater than 17 rounds.

However, there was the Hill 9mm SMG, which -- decades before the P90 -- had a long, straight, top-mounted (and transparent) magazine. Since the 9x19 case has significantly more taper than 6.5 Grendel, now I'm not so sure it wouldn't work.