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ARAK. That’s AR as in AR-15, plus AK as in AK-47. From Faxon Firearms, the ARAK-21 is a long-stroke gas piston upper receiver with a self-contained recoil system that fits on any standard AR lower receiver.

As you’d expect, it shoots the AK-47’s 7.62×39 caliber, but also switches in about three minutes to 5.56 or 300 Blackout. And best of all, it works.

Faxon sells the ARAK as a complete rifle (the ARAK-21 XRS) as well, but for those of us (all of us?) who already own various AR-15 lowers there are obvious advantages to simply mail ordering an upper for delivery right to your door. In my case I borrowed an ambidextrous ejection ARAK-21 upper with 16-inch 7.62×39 barrel, 16-inch 5.56 barrel and 12.5-inch 5.56 barrel and went to town.

The monolithic upper receiver sports a quad rail forend, though the side rails and bottom rail are easily removable. As the upper isn’t exactly a featherweight — 5.5 lbs with a 16-inch medium-profile barrel — I appreciated the ability to ditch extra rail estate that wasn’t being used. Especially on the left side, the naked forend was also more comfortable to grip.

Flipped upside down to view the 6:00 side, not only is that section of Pic rail removable but so, too, is the entire bottom of the forend. Using the included hex wrench, simply loosen those six, captive bolts to lift the baseplate off.

With that accomplished, slide the barrel about an inch forward and it’s yours, lifting cleanly out of the ARAK. Install a different barrel, insert the bolt carrier so it locks into battery, then tighten everything back down. In about three minutes the end user can swap barrel lengths, profiles, and even calibers.

The bolt carrier and its attached piston ride on a hardened steel rail system bolted into the receiver. A sleek recoil spring nestles down into the hollow tube behind the solid steel piston, and is contained within the upper. As no traditional AR-15 recoil system (receiver extension, buffer, spring) is needed and the bolt carrier doesn’t cycle outside of the receiver, the sky’s the limit for stock choices. Including folding stocks, wire/skeleton stocks, etc.

Different bolts are required for 5.56/300 BLK and 7.62×39, and are easily swapped without tools. There’s a firing pin spring for the NATO-based rounds, which isn’t used for the commie stuff.

Eight-lug bolts have dual ejectors for all calibers. With an extractor located at 3:00, a simple 180° turn of the bolt switches ejection from right- to left-side.

Ambidextrous ejection is an option — a no-cost one — on the ARAK-21. The receiver can also be ordered with a solid left wall for right-hand-only ejection.

Up front is an adjustable gas block with four settings: high, medium, low, and off. High is for dirty or adverse conditions to provide some extra oomph to the carrier, medium is for normal use, low for suppressed shooting, and off for single-shot operation (extra quiet when suppressed, too). The tip of a cartridge can be used for additional leverage, if needed, when clicking between gas port settings.

Continuing the ambidextrous theme, the ARAK’s spring-loaded, forward charging handle can be switched from left to right side without tools. It’s non-reciprocating, meaning it stays in place while shooting and won’t shear off any of your digits. That’s a plus.

On the downside, since the charging handle only works to push the bolt carrier rearwards it can’t be used as a forward assist, a feature — debated in utility as it is — that the ARAK-21 goes without.

I appreciate the location of the charging handle, as it allows for locking back the bolt one-handed. Pull the charging handle to the rear with your index and middle fingers, then use your thumb to depress the bottom of the bolt catch before releasing the handle. Strong hand remains on the pistol grip the whole time.

On the range, I was initially frustrated with light primer strikes on Wolf brand 7.62×39. Obviously surplus and steel-cased, Russian AK food is known for having particularly hard primers and, having simply been handed this upper without a primer (of the knowledge kind; rhymes with “trimmer”), I missed all of Faxon’s clear statements about hammer spring strength.

Both the website and the owner’s manual make it known that a full- or even high-power hammer spring needs to be used on an AR-15 trigger in order to achieve reliable ignition of this type of 7.62×39 ammo. Faxon particularly recommends either a Wolff high-power hammer spring or a HiperFire trigger in their stiffest spring configuration.

Swapping over to a random polymer lower receiver with a standard Mil-spec (“parts kit”) trigger in it, the light strikes disappeared and I ran through 220 rounds of Wolf without a hitch.

About 60 of those rounds were fired suppressed with my Dead Air Sandman Ti gracing the muzzle. Normally it’s a terrible idea to throw your suppressor on a random AK-47, as they’re notorious for not having concentric threads or even a centered bore, but this isn’t a random AK. It may be firing the same cartridge, but Faxon’s reputation and business ride primarily on their excellent rifle barrels and the nitrided 4150 (or 416-R stainless) barrels in the ARAK are no exception.

But good lord was there a lot of gas jetting out the left-side ejection port! Though I had the ARAK ejecting empties to the right and the gas port turned down to low, every shot blasted my face with hot gas and debris.

Faxon is addressing this with an ejection port cover, which is easily installed in place of the left-side case deflector. While I received a 3D-printed prototype version rather than the final product, it was a lifesaver. Complete night-and-day difference with no perceptible gas in my face whatsoever.

Over to the accuracy department and I was shooting about 3.5 MOA with the 122 grain, steel-cased Wolf ammo. Which is acceptable for a short-range battle rifle but not particularly good, though to be fair it’s the rare gun indeed that could shoot this ammo (which is good for about a 40 fps standard deviation in velocity) any better.

Unfortunately — a glaring failure, I know — this is the only 7.62×39 I had available. With better ammo I don’t see any reason not to expect results more in-line with the 5.56 results below, considering the company involved and the identical barrel construction and firearm.

With the 16″ 5.56 barrel the ARAK shot groups from 1 MOA to 1.45 MOA, effectively in-line with how much the ammo cost. Inexpensive CapArms 55 grain reloads shot the widest groups while Federal Gold Medal 69 grain and IWI RazorCore 77 grain shot the tightest.

Considering this is far from a free-floated barrel, with a trunion 12″ down the pipe that’s clamped into the handguard and also supporting the gas block responsible for kicking the piston and carrier rearwards, I’m happy with one minute accuracy. Presumably if I slowed down the shot cadence these groups would tighten up, as nearly all of them exhibited vertical stringing due, most likely, to the barrel heating up from a cool state.

If you’re looking for a survival, bug-out, TEOTWAWKI, or battle rifle, the ARAK-21 would be a solid choice. We found it to be flawlessly reliable (with a full-power hammer spring), stoutly built, and highly adjustable. The ability to swap between calibers within about three minutes is awesome, while easy gas system adjustment and ambidextrous charging and ejection are icing on the cake.

Specifications: Faxon Firearms ARAK-21 Upper Receiver

Caliber: Interchangeable between 5.56×45, 7.62×39, and/or 300 Blackout
 long stroke gas piston, adjustable
Barrel Length: 12.5″, 16″, and 20″ barrels of various profiles are available
Twist Rate: 1:8 in all calibers
Weight: 5.5 lbs with 16″, medium profile barrel.
MSRP: $1,199 in black with one 4150 barrel. Add $200+ for additional barrels and $100 for an additional bolt and firing pin, if needed.

Ratings (out of five stars):

Reliability * * * * *
The ARAK runs very strongly. It cycles, ejects, feeds, and locks into battery with smooth authority. Short of torture testing the thing, it’s a clearly reliable system. And there’s always the high gas setting to power through built-up crud.

Accuracy * * * *
1 MOA from a battle rifle is better than average. 1.4 MOA from inexpensive reloads is better than average. 3.5 MOA with Wolf 7.62×39 is likely better than average, too.

Ergonomics * * * *
Ambidextrous design and a forward charging handle is five stars all the way, as is the self-contained recoil system allowing for folding stocks and other non-typical-for-an-AR stock choices. However, the weight and it’s associated front-heavy balance knocks it down to four stars.

Design * * * * *
An adjustable long stroke gas piston, caliber-swapping, ejection side-swapping, self-contained recoil system AR-15 upper receiver? Awesome.

Overall * * * *
Yes, I realize that complete and perfectly functional AR-15s and AK-47s can be had for hundreds of dollars less than the ARAK-21 upper receiver’s starting price of $1,199. But do they have the features mentioned in the other ratings categories here? Can they quickly and easily switch calibers? No and no way. The ARAK-21 is a heck of a piece of kit.

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  1. $1200 for an upper is one seriously spicy meatball, one that I don’t think I could choke down.

    • Yes, it is spicy and hard to swallow. I bought one and i like it. The front end is 100% proprietary and inflexible as far as options…. but, i wanted an ambidextrous, forward charging piston driven gun (like adcor’s BEAR), with a more robust bolt head (because piston AR’s beat up 7 lug bolts), a quick change barrel system, and no buffer tube crap (like the RRA/zm300/every other rifle in the world). I also wanted it to have parts compatibility with my other AR’s.

      Faxon was/is the only option. If I wasn’t looking for that specific and narrow set of things, then I would have never bought it. Its heavy and the bore sits too high for anything other than low mounted red dots, iron sights, or 24mm-30mm objective lens scopes.

        • Yes that would be a waste…. you can’t have an evil feature like that on a rifle in California…. say,… like a LAW Tactical folder to make it compatable with your other AR’s if need be. That would be super bad and you can’t have that.

  2. “$1,199 in black with one 4150 barrel. Add $200+ for additional barrels and $100 for an additional bolt and firing pin, if needed.”

    For the upper. Ouch. As nice as it appears to be, pass.

  3. I really like Faxon barrels, have several. Good quality at a good price. Can’t go wrong with Faxon.

    I think a hammer forged 4150, 5r, .223 wylde, nitride with np3 or nickel boron extension would be the bees knees.

    Faxon just came out with a match series similar to what I mentioned, but 416-R instead of hammer forged 4150.

  4. So I could get a AK and AR (with matching serials) for less than 1000 USD when PSA does a sale and I don’t need the AR platform 7.62×39 mags that don’t really work that well while costing more than an AK mag. What am I paying the extra for?

  5. What 7.62×39 AR mags did you use? Any issues with them?

    I’ve been considering a PWS upper in 7.62×39 that’s available locally but have heard mixed stories on what mags are okay.

    • Admittedly I did zero research on 7.62×39 AR magazines. I suddenly found myself with this upper for review so I just bought the first mag I came across, which was an ASC via Primary Arms. I got the 30-round one. I had to down-load it to 20 rounds (which is convenient enough considering cheap 7.62×39 is in 20-round boxes) to get it to function reliably. It would often fail to feed rounds up if I loaded much more than 20 in there. Literally they’d just stick in the body and hang out without the next one coming up to the feed lip. Seems like the curved part of the mag doesn’t work quite right and the follower isn’t happy down there. Possible that taking it out and lubing the sides of the follower (I know, generally a no-no) with a very light oil or a graphite dry powder or something would cure it, but I didn’t bother to try as I was satisfied to just load 20 at a time for the 11 mags of 7.62 I put through it. The Lancer L5AWMs I was using with 5.56 obviously worked great.

      I’ll ping a couple folks, Faxon included, to see if they have recommendations.

      • Thanks – much appreciated! I’ll be very interested in hearing Faxon’s response. This is a very interesting alternative to the PWS upper I’ve been eyeballing.

        I’m not too proud to admit that either way I’d be spending upwards of a kilobuck for what would basically be a range toy – and me a lousy rifle shot to boot – but if I get it I want it to run right darn it! 🙂

  6. Jeremy,
    Who was the manufacture of the 7.62×39 magazine? Did you have any feeding issues w/the mag???

    Thank you,

      • Jeremy,

        Sorry, I missed that comment… Don’t any oil to the mag, find an AK mag spring and test in the AR mag. If the spring doesn’t fit cut 1 or 2 rungs. I have an RobArm XCR-L i used both 5.56 and x39. I’ve had to modify the ACS mags. Also try the CProducts mags. I have a couple I can loan you. I’m in the Austin area. Let me know.

        Thank you,


      • I’ve found that C Products AR15 mags are HORRIBLE. OK the one I have – the follower is garbage.

  7. The one thing to keep in mind if you own various barrels is make sure right ammo for that barrel. I know Jeremey you say it can’t be done, but with enough stupid, a .300BLK can be chambered and go BANG with ugly results. They do mark their .300BLK differently for those that may have 5.56/.300BLK. Also offer different color “rubber bands” marked with 7.62×39 and .300BLK.

    The also offer military and LE discounts on all their products.

    • Many people have accidentally chambered a 300 BLK in a 5.56 setup and caused a kaboom. I’ve warned about that on here previously. Not sure why you suggested I say it can’t be done, as that’s definitely not the case (it can be done and I have discussed it)…

  8. What is that rifle holder hooked to your bag in the last picture? brand, where to acquire and such?

    • So, it comes as standard equipment on Triple Aught Design’s FAST Packs. I own the Lightspeed (smaller) version, which is seen in the photo. They also sell the part you’re talking about, the“FAST Transporter Tail”, separately, with and without MOLLE webbing. It’s certainly possible that you could attach it to a pack you already own if it has webbing or other attachment points on the bottom or on the front bottom. Perhaps the coolest part of having it on the TAD FAST Pack is that it can be flipped up so it’s buckled flat on the front of the pack, where it can be used to hold a helmet or sleeping bag or blanket or jacket or whatever, or even buckled into the inside of the pack to secure a laptop or water bladder or MOLLE stuff, etc.

  9. I have had my Colt Sporter Lightweight in 7.62 x 39 for twenty years and shoot about 1,000 rounds per year out of it
    The best magazine by far is the C products one
    ASC and C products have a history with lawsuits and machinery going back and forth
    Both work fine, as do the old “frankenmags” with AR upper halves welded to AK lower halves
    A .223 magazine will feed five 7.62 x 39 rounds just fine in a pinch

  10. I’ve heard that you can use this upper with SIG MCX lower – this is how you get a sturdy lightweight folding/collapsible stock with no redundant buffer tube business.

    I asked Faxon on their Facebook whether ARAK is compatible with MCX lower. They said that it should be, so that’s encouraging.

    But I haven’t seen anyone try yet. That would be an interesting experiment.

  11. Very nice, I REALLY like it. There’s always people who say too much money, not worth it, I can buy 5 of this instead on one of that and so on. I will state upfront that I wish there were alternatives to the handguard – that’s the only thing I don’t like so much – no doubt that thing is gonna get hot in rapid fire mode. I don’t believe in throwing my money away and I’m a bit of a penny pincher BUT I think Faxon has created an AMAZING product here. I’ll be saving my pennies.

    • I have a hard time understanding why so many feel the need to make the argument that they could have X number of AR15 rifles for whatever something like this cost.

      The AR15 is in a unique position that no other firearm has ever found itself. There are probably over a thousand vendors that actually manufacture interchangeable parts for them. Competition being what it is, you can build or buy a pretty decent rifle for less than $500 with a nitrided barrel. No other rifle can match the endless customization or low cost of the AR15. I think everyone understands that.

      I just don’t understand why people have a hard time understanding why new products cost more. Someone has to pay for the engineering and testing. Proprietary parts made in much lower volumes also cost more to produce. Some rifles like the IWI Tavor series also have the additional cost of setting up a US importer to stock parts, handle warranty claims and support. All of this cost money and if we want new designs to come to market and become affordable, someone has to pay it.

      Compared to some of the other piston driven custom AR15 designs, the ARAK is not unreasonable, especially with the ability to easily switch calibers. I won’t be buying one, because I really don’t have a need for one. But if you want to shoot suppressed or just want to have something different from what everyone else has at the local range, it looks pretty cool.

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