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 designed by AR57 LLC was produced by AR57 of Kent, Washington, USA. The company is now defunct. 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 and was marketed as a competitor to the P90 and other personal defense weapons.

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  1. C

    Ar57 upper 5.7x28 !!!

    Hey fellas, just wanted to pass on a little info I found out yesterday... so I have a fn 5.7 pistol and was thinking of getting ps90 but they are pretty spendy and hard to find... found out yesterday they make ar57 uppers that fit on ar15 lowers for about half of buying a ps90 ... I'm getting 1...
  2. wired

    Newest addition to the family

    Ive been accelerating my stamp collecting in anticipation of 41P ( Like everyone else ) . Not that I can't get one signed by the CLEO its just that I don't want my face to be one that the local fuzz recognize. In any case this is my 9th of the year. Been really stepping it up with the SBR's in...
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