AR Five Seven: 5.7×28mm AR Upper
This is very interesting. A one piece 5.7×28mm modular upper that attaches to a AR-15 lower receiver and uses 50 round FN P90 magazines.
TrueWPN at AR-15.com took these photos. Click to expand.
Well this thing is interesting. Its a AR-15- PS90 cross bread. The one piece modular upper snaps onto any AR-15 lower. Allowing you to fire 5.7×28mm with the PS90 50 round mags. I added HK 416 rifle sights. I wanted to use the LaRue Tactical Aimpoint mount in the picture but I think the sight may stick out to far to mag change:( we will see. I just used a DPMS complete lower with a Magpul grip and stock. It has a right side charging handle. The upper and lower color match perfect. I am really impressed with the quality.
It still has the bolt open feature like the AR-15. It does utilize the buffer tube with the stock AR spring and a Heavy buffer that came with it. It ejects the spent cases through the mag well. I had a cheap 30 mag that was no good so I gutted it and cut the top off so it will work as a funnel for the spent cases. I purchased the Upper from www.HKSpecialist.net who shipped and I received it over night. Great guy to deal with. Unfortunately I can’t find them for sale anywhere else and I got the only one Gordon had left. The Manufacturer’s web sight is www.57center.com . I put 150 rounds down the pipe today after work with out a hitch. Really sweet accuracy at 50 yards open sights. And it was easy to engage multiple targets with no recoil throwing me off. I cant wait to put a optic on it. I am leaning towards a Aimpoint Micro T-1. Enjoy the pics…………………

The 5.56mm AR magazine is not used.
These photos are from the 57 Center’s website.
Hat Tip: Defense Tech





Okay. Why?
why not? Since when have gun enthusiasts needed good reasons for spending money on new toys?
Tru dat. WTF.
I did ask but they could not give me a “base” price.
Does seem rather a nifty toy. Mind you, I’d want something to plug up the magazine area to keep dirt out. Not a magazine proper, but some form of plastic/rubber plug.
How about the hot brass spilling out onto your arm? The PS-90 doesn’t have much of an issue with that because of how the weapon is held, but an AR-15 would seem to have an issue with the ejection from the mag well. Some sort of catcher may be a good idea. A short barreled version would be interesting, maybe a ten inch with a supressor added.
I just picked one of these up.
Put 200+ rounds through it no problem.
Its nice to have a very light AR with 50 round capacity.
With an empty 30rd AR magazine its a great brass catcher so not only is there no hot brass flying around theres nothing to pick up – great for re-loading. Also I have a pretty big investment in the PS90 and the magazines and the 5.7×28 ammo and re-loading dies so this was a very nice addition that gives me a less expensive alternative to having another carbine that shoots 5.7×28.
Also with the price of the 5.7×28 dropping now that its being made in the US its getting very cost effective to shoot.
Davis, using the magazine as a brass catcher is awesome! How many cases can a 30 round mag hold before you need to empty it?
It should hold 50 but it would be tight. I know for a fact 20-30 is not a problem. you have to cut a little of the top of the magazine off. I figured I would have to cut the feed lips off to ensure there wouldnt be a blockage. However you actually have to cut a little more off so it clears the bolt. I also smoothed the internal edges so it wouldnt catch/snag on anything. I also placed some small ammounts of soft sided Velcro on the inside bottom of the magazine to soften the first few case ejections so the cases shouldnt deform on ejection.
I know people think I’m probably nuts for cutting a Sig Arms 556 magazine but I wasnt about to cut any of my HK magazines up.
http://www.make-it-so.com/Guns/PWarms/ARcenter/jpegs/Magazine1-small.jpg
http://www.make-it-so.com/Guns/PWarms/ARcenter/jpegs/Magazine2-small.jpg
Base price is 699.95 without the PS-90 Mag.
the coming together of the 2 best firearms in the world.(in my opinion)
The ar-fiveseven upper I put on my lower is more than I hoped for. It worked perfectly, with no problames at all!! Accurate to sub-moa at 50 yrds. and good to 100 with a propper scope. Moreover, any one with a suppressor for the 223,(it will thread on to this barrel) will find the only noise is the recoil buffer slamming past your ear in the tube.(with sub-sonics) Of-course a bit of a crack with standard 5.7 ammo. This set up, with an EOtech or other such sight is nothing less than a pleasure to shoot. I am only put off by the the length of the upper rail. The rail of the upper by necessity is short, so no bad-ass set-ups with magnifiers and such, but with three full length rails at 3/6/9 o’clock at no extra cost, it more than makes up for lack of top rail.
Davis, How does the thing operate? The site says it’s recoil operated, but I want to make sure the bolt is actually locking somehow before I buy one.
Please tell me it’s not straight blowback…