AR Five Seven: 5.7x28mm AR Upper

This is very interesting. A one piece 5.7x28mm modular upper that attaches to a AR-15 lower receiver and uses 50 round FN P90 magazines.

TrueWPN at 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 5.7x28mm 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 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 . 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…………………

 Albums C108 01Coltcolt Ar-57008
The 5.56mm AR magazine is not used.

 Albums C108 01Coltcolt Ar-57007

 Albums C108 01Coltcolt Ar-57004

These photos are from the 57 Center’s website.

Picture 13-13

Picture 8-18

Hat Tip: Defense Tech

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • 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.

  • Tractiongrips

    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.

  • Davis

    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.

  • D

    Base price is 699.95 without the PS-90 Mag.

  • nick

    the coming together of the 2 best firearms in the world.(in my opinion)

  • Ethan

    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.

  • bob

    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…

  • Kirk

    Anyone taken 150 yrd plus shots?

  • noname

    Look, to the people asking why, and also the people asking “well what gains do you get from running it?” : First off, not everyone needs a .223/5.56 round to get the results you want. In fact, in a home defense/ defensive gun, it is actually better to not have rounds that can travel through multiple walls.

    Second, with an empty ar mag, you won’t leave any brass like mentioned. This is good if you like to reload.

    Last, is the most important trait of the 5-7 upper. THERE IS NO GAS SYSTEM. That being said, it will be more durable than an AK, and need next to no care to operate. Not that you would want to do that to such a nice upper though. Basically the only parts you need to maintain is the bolt. (firing pin springs etc). Outside of that there is nothing to mess with.

    One more thing… is unlike other monolithic ar uppers, you get a monolithic upper, full floating heavyweight barrel, and a nifty flash, for about as much as a low end to semi decent 5.56 upper would run you (and no not talking ar monolithic uppers as those generally run 1300+).

    Just gotta look at the pro’s and cons.

    I love my upper. It’s solid as hell, but doesn’t fit ultra tight to my Lauer LMT lower. Bah. Either the lower or upper tolerance is off. I’m betting it’s my lower being it’s been used with several uppers over time.

    Troy micro battle sights mate up perfectly with the upper btw 🙂

  • rob

    I got to play with one that a friend brought to the range. I dont see the point. 223 ammo is much cheaper and much easier to find. If you want a home defense gun , a shotgun is better than a rifle. I see testimonials from guys that have all kind of criminal justice background that say this gun is all that; I dont know what criminal justice has to do with knowing anything about guns . The fact is.. its weird, ammo is expensive,mags are scarce and expensive, and the round itself does not do anything that another round wont do. Buy a 223 and save yourself some headaches.

  • Jorge Gonzalez

    I bought one of those tactical rifles for my daughter the AR 5.7×28 mm which has a really light recoil and very appropiate for women but I would like to know if there is a lower magazine for it I’ve been looking for one here in the internet but I haven’t been able to find one. If you know that there is one available please let me know cuz I dont really like the upper magazine for it. Thanks I hope somebody can help me.

    • Dave A.

      FN, ATI, and PWA (AR Five Seven) all make 10 round magazines, if that’s the question you’re asking.

      Avoid the ATI- the FN works best, follwed by PWA/AR Five Seven

    • Dave A.

      Oh- I see what you meant.

      No- there is no such thing as a lower magazine- the 5.7 upper only feeds from the top.

      You can use an empty lower magazine to catch spent brass, but it has no other function.

  • Perhaps I can lend a hand on the “why” question. The specifics of this unit that appealed to me are: (1) Bottom-ejecting brass, so you don’t lose it; (2) VERY low recoil, so you can see your hits if you’re shooting varmints out to 200 or so yards; (3) 50-round capacity; (4) Simple, blowback operating system; (5) Major versatility with all the rails to mount loads of accessories on the thing; (6) WAY less noise than a .223/5.56, in case you need to do some shooting in an area where excessive noise would be a problem; (7) Excellent accuracy; (8) Very good quality/reliability for the price. So far I’ve put a couple hundred through mine with nothing but extreme satisfaction. A product of this quality at a decent price is a rarity these days. Quite a pleasant surprise.

  • AR Guy

    I believe the reasoning for the 5.7 was to be better at penetrating body armor than the 5.56. Why would anyone who already has AR-15’s need this? Because it is WAY cool!!! What lower is recommended, if any.

  • William Pope

    This is by far not only the most fun upper that I have for my AR’s, but it is also practical. With magnifcation 200-300 yards is perfectly attainable. I shoot within 200 most of the time and can shoot 2MOA+ a little on a bench. The only issue I ever had was with a custom trigger (that I installed – there probably being the issue), and it fired just like a select fire firearm. Loved those few minutes of illegality. Got the trigger cleaned and reinstalled and I had no issues.

    need to reload because of the cost of ammo, but that is with all ammo now. Personal defense – ideal, maitains a perfect zero on target because of almost no recoil. Perfect for animal control up to the size of a coyote. Not a deer gun, but what a dear set up. Love it.

    • Bob Bell

      I was wandering if you know of a 5.7×28 upper that would work on a DPMS LR-308 lower and if you are the infamous Willie P. from Vicksburg, MS I know from Church? If so let’s go shoot sometime. BB