Factory New – comes with a 16″ lightweight barrel with M-LOK rails. This AR57 AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7×28 ammunition. The unique upper design of these AR15 Upper Receivers loads from the top and ejects downward through the AR-15 mag well. The new generation upper has a stronger, lighter, and more streamlined rail; finished with a beautiful ultra-smooth melonite black coating. Convert your AR-15 type rifle to shoot the same 5.7×28 ammo as the legendary FN P-90 PDW! This AR57 Upper is constructed with a steel barrel, muzzle brake, bolt carrier group, buffer, and screws, all built into an alloy monobloc receiver. In other words, it is ready to drop in and push pin. It is also built as solid as a tank. A single block of Aircraft Grade 7075 T6 aluminum, referred to as Kryptonite Monobloc and rated at 83000 PSI strength, is used for the receiver and its component rails. Precision milled to within .002 tolerance, this upper is chambered in 5.7 x 28 mm. The barrel is 16 inches with a perforated muzzle brake attached on 1/2 x 28 threads making the overall length 18 inches; the bore is six groove right hand 1:8.5 FN twist. The sight system is a 13 slot Picatinny over the operating handle, with 3-slot upper and lower forward rails. The metal parts, including receiver, rail, barrel, and bolt, are melanite treated for a hard, durable finish. Bolt is made from 8620 alloy. The receiver and rail block measures just over 17 inches overall length; from the receiver back to the muzzle end, the total length is 24 9/16 inches. In contrast to many other receivers, there is no gas system to become clogged with carbon or fouling; the chamber stays clean well beyond extended shooting. Extremely reliable, simplicity is key, with the free sliding bolt being the only moving element and its easy removal makes maintenance literally a snap. The AR-57 system ejects spent rounds through the lower’s magazine well. *Does not include the magazine. Specifications for AR57 ULT 16in Barrel 5.7x28mm Upper Receiver Assembly: Manufacturer: AR57 Cartridge: 5.7x28mm Overall Length: 18 in Barrel Length: 16 in Threads per Inch: 1/2×28 Fabric/Material: 8620 Alloy Gun Rail: M-LOK Gun Type: Shotgun Condition: New Magazine Included: No Package Contents: AR57 ULT 16in Barrel 5.7x28mm Upper Receiver Assembly
6 reviews for AR57 ULT 16in Barrel 5.7x28mm Upper Receiver Assembly
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TJ –
Bought this and an put it on a Aero Precision Lower and it functioned fine. I recently fired it for the first time and it cycled pretty well putting 150 rounds through it, 2 jams out of 150 that cleared right away using American Eagle 5.7 range ammo and genuine FN Mags. Haven’t fired genuine FN ammo yet. My only concerns when I first got it was that my local gun store tested it after putting in the supplied buffer tube and the charging handle seemed to be shaving off metal flakes so definitely needs to be well oiled before firing. The other thing I need to check on is there were what appeared to be brass shavings inside the magazine port which I’m not sure what was causing that. Over all was pretty happy with it first day on the range it easily connected to the lower and I was happy I could catch all the brass with a hollowed out regular AR mag.
Armando Gomez –
Took to the range, it would never fire. It would load from magazine but firing pin isn’t hitting the primer. I believe it’s not going in to the extractor correctly. Looks cool. Wish mine would function.
Dan –
Ad clearly shows the magazine mounted on the unit. After receiving the unit i had to scour the ad looking for the lack of a magazine. So hopefully you will see this. I haven’t shot it yet… guess why.. seems pricey for an upper
Freddie –
I had this upper fixed onto a cheap Anderson arms lower for around a month marinating in clp before I was able to take it out to the range. The anticipation was killing me from the mixed reviews here, with even some of the positive ones claiming jams. Had a blast plinking steel from 75 yards. 500 rounds later while sighting in a red dot, it didn't jam a single time. Crazy powder fouling is to be expected but honestly just makes cleaning that much more satisfying. All in all, I'm more than happy with my order and will definitely be recommending this upper.
Claytonian –
This really is the coolest add-on you can buy if you have an AR15. You don't need to do anything. You just switch the uppers. The 5.7 magazine sits on top of the upper, so no adjustment to the lower on your AR. In 30 seconds, you can go back and forth with two different calibers on your AR. The cartridge ejects through the mag well. Well built and looks super sleek! Highly recommended!
Solid Snake –
I think this company sent out of business because they couldn’t get it to cycle correctly , I believe these are all old stock. Good luck getting any support, you’re better off reading the forums. Do not use the buffer that is included and instead order a 9mm heavy buffer, around 7oz. Oil it and shoot it, use FN mags, and you might get lucky and have it run. The fact their included buffer doesn’t work is ridiculous though