The AR-57, also known as the AR Five Seven , is a Lower receiver for the AR-15/M16 rifle and an Upper receiver, firing 5.7×28mm rounds from standard FN P90 magazines. It was designed by AR57 LLC and is currently produced by AR57 of Kent, Washington, USA. The AR-57 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 FN 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. Hollow AR-15 magazines can be used to catch spent casings.
Unlike the standard AR-15 configuration which uses a gas-tube system, the AR-57 cycles via straight blowback. A full auto version exists marketed as a competitor to the P90 and other personal defense weapons.

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  1. arakboss

    AR Upper Sellers May Want To Revisit Pricing or Ad Descriptions.

    If you search for "upper" in classifieds, the list is fairly long, especially for uppers with barrels under 16". Prices seem high to me but maybe their ad descriptions aren't up to snuff. (Edit: Or buyers are cutting back on upper purchases)
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