AR-57


The AR-57, also known as the AR Five Seven, is available as either an upper receiver for the AR-15/M16 rifle or a complete rifle, firing 5.7×28mm rounds from standard FN P90 magazines.
It was originally designed by Rhineland Arms but produced by AR57 LLC.

Design

The AR-57 Personal [defense weapon|PDW] upper is a new design on AR-15/M16 rifles, blending the AR-15/M16 lower with a lightweight, monolithic upper receiver system chambered in 5.7×28mm. This model is also sold as a complete rifle, supplied with two 50-round P90 magazines. The magazines mount horizontally on top of the front handguard, with brass ejecting through the magazine well. AR-15/M16-based STANAG magazines can be used to catch spent casings by taking out the feed lips, spring and follower. Sheet metal brass catchers can also be used on the AR-15/M16 lower.
Various scopes and other accessories can be mounted on the picatinny rail.
Unlike the standard AR-15 configuration which uses a gas-tube system, the AR-57 cycles via straight blowback. A fully automatic version exists and was marketed as a competitor to the P90 and other personal defense weapons.
Suppressed versions are also available.

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