MasterPiece Arms MPA Defender MPA57DMG

Semi-automatic MAC-pattern 5.7x28mm pistol, side cocking with a Picatinny top rail, 1/2x28 threaded, feeds from FN Five-seveN pattern magazines.

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Key Highlights

•MAC-pattern semi-auto host in 5.7x28mm
•Picatinny top rail from the factory
•1/2x28 threaded barrel

Specifications

Price: $647
Weight: N/A
Calibers: 5.7x28
Rail Type: picatinny
Best For: range training home defense

Capability Profile

0-10 Scale Across 8 Axes

Compatibility Tags

family: pccmag-type: mpa-defender-57mag-type: fn-five-seveninterface: picatinny-topbarrel: ultra-compactthread: 1/2x28

Overview

The MPA57DMG is the 5.7x28mm Defender: the same MAC-pattern straight blowback receiver as the 9mm MPA30T, rechambered and re-cut to feed FN Five-seveN pattern magazines. It is a serialized semi-auto pistol, not a registered machine gun. MasterPiece Arms lists it at $750, and Classic Firearms and KYGUNCO have carried it in the $640 to $650 range.

The two changes that matter against the 9mm gun are the cocking handle and the magazine. The 57DMG cocks from the side, which frees the top of the receiver for a Picatinny rail, so a red dot mounts without the aftermarket rail adapter a top-cocking MPA30T needs. It feeds from FN Five-seveN pattern magazines in 20 and 30 round capacities. Those do not interchange with the 9mm Defender's grip-fed magazines in either direction.

The barrel is threaded 1/2x28 and the gun ships with a muzzle brake. As with every blowback MAC, the action is not gas-sensitive, so a 5.7 can bolts on without any tuning.

Key Features

Semi-automatic straight blowback action in 5.7x28mm
Side cocking handle, which leaves the top rail clear
Picatinny top rail from the factory
Factory 1/2x28 threaded barrel, ships with a muzzle brake
Machined aluminum lower receiver and aluminum grips
Front and rear adjustable sights
Feeds from FN Five-seveN pattern magazines in 20 and 30 round capacities

Pros

+Picatinny top rail as shipped, so an optic mounts with no adapter
+Threaded 1/2x28 from the factory and blowback-insensitive to a can
+Takes widely available FN Five-seveN pattern magazines rather than a single-source proprietary mag
+5.7x28mm gives flatter trajectory and less recoil than the 9mm Defender

Cons

−Roughly $150 more than the 9mm MPA30T, and 5.7x28mm ammunition costs more per round
−Magazines do not interchange with the 9mm Defender at all
−Needs a rear stock or brace adapter before it is controllable at speed

Detailed Specifications

caliber: 5.7x28mm
capacity: 20+1 with the factory magazine; FN Five-seveN pattern 30-round magazines also fit
Gas System: Straight blowback
trigger: Single stage
msrp: $750
handguard: None; bare upper with a side cocking handle
Muzzle Device: 1/2x28 threaded barrel with a muzzle brake
Receiver: Machined aluminum lower receiver
Finish: Black Cerakote