MasterPiece Arms MPA Defender 20-Round Magazine (5.7x28mm)

The 5.7x28mm MPA Defender feeds from this factory 20-round polymer magazine, and nothing else. It is not a variant of the 9mm 30-round magazine and the two do not interchange; the cartridge is a different length and diameter, and the magazine is built around it.

Capacity drops to 20 rounds, which is a consideration if you are running a forced reset trigger on a 5.7 host. The 5.7's low recoil impulse actually suits a forced reset device well, but you will be reloading more often than a 9mm shooter.

At $57.39 it is the most expensive magazine in the Defender line, which tracks with 5.7 magazine pricing across the board.