i was thinking of building an ar57.......the uppers are about $700.....
and use a p-90 50 round mag on the top ...then ejects out the ar mag well
.....the mags are pricy like $70.........
but 500 rnds of ammo is $199
it uses the 5.7x28mm.........
i got a couple mega lowers comeing and want something a little different ...just wondering if anyone has one and if they like it or not?....