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Serbu Firearms is best known for their SUPER-SHORTY shotgun, which I reviewed here a few months ago. That certainly isn’t their only product, though, as Mark Serbu and the gang have been manufacturing a semi-auto .50 cal and an affordable ($1,900) bolt-action .50 cal in addition to a buffer tube-less AR-15 for years. In collaboration with an interesting YouTube personality, Serbu is now offering a .50 BMG (or .50 DTC) rifle at an introductory price of only $875. Which is pretty crazy. But, yes, there’s a bit of a catch . . .

You see, that YouTuber is Royal Nonesuch. His ~131,000 subscribers come to see his homemade firearms, which are often hardware store creations. As in, plumbing parts and galvanized pipe. Serbu borrowed him to aid in their quest of creating the simplest, least expensive .50 cal rifle possible. The result is the break-action, single-shot RN-50 with a muzzle brake.


Of course, it isn’t a hardware store special and Serbu is machining it out of actual ordnance steel and such. But it is a single-shot in the style of Mr. Royal Nonesuch — which is much like various other breech loaders — in that the rear of the breech must be opened up in order to insert a round into the chamber or to remove a spent case. On the RN-50, it’s a thread-on breech cap that secures the round inside of the chamber and houses the firing pin.


So it won’t win any speed shooting contests, but it will help one’s .50 BMG ammo budget last a little longer. It’s also a simple, lightweight solution for long range shooting. In fact, with 29.5″ barrel the whole shebang is only 17 lbs. Okay, that isn’t light, but it’s light for a .50.

The RN-50 accepts AR-15 pistol grips and buttstocks, and has rails for mounting an optic and a bipod. Apparently it’s an accurate rifle, too, which I may just find out for myself if Serbu ends up loaning me one. As it states in the flyer below, $875 is an introductory price. I’m not sure how long that’ll be good for, but MSRP once these go into full-on production still won’t hit four digits.


Here is more on the rifle from the manufacturer:

Our newest .50 caliber rifle – as well as the most affordable, the RN-50 is a break action with threaded breech that just can’t be beaten.


The RN-50 represents the first time a production firearm has ever been inspired by social media. Designed in conjunction with YouTube celebrity Royal Nonesuch. The RN-50 is a unique approach to the .50 BMG single-shot rifle. Rugged, lightweight, accurate, easy takedown and low price make this rifle a winner! The simple screw-on breech cap is not only strong, it applies absolutely symmetrical support to the cartridge case, allowing for incredible accuracy. Using top quality materials as well as parts from our proven BFG-50 rifle, the RN-50 gives you high quality at an incredible price, along with lineage to a safe, proven firearm that’s been in production for 17+ years. Whether you’re looking for the least expensive way to get into shooting .50BMG or you want to outshoot your friends’ expensive match rifle, the RN-50 is for you!



.50 BMG, .50 DTC (+$250) for restricted markets.


Modified break action with threaded breech

Barrel Length and Options

29.5″ (standard), 22″, 18″ (+$125), 36″ heavy (+$250), all alloy steel with 1-in-15 button rifling


Heat-treated steel and aluminum construction


Manganese phosphate and hard anodized



 © Serbu Firearms, Inc. 2019. Specifications subject to change.



RN-50 Manual

RN-50 Exploded View




No matter which scope you get, make sure that it is rated for .50 BMG recoil. The two listed below both are.

SWFA Model SS – approx $350

Millet Model LRS – approx $400-450 depending on when and where you get it.


You want low height rings. We recommend IOR Valdada low rings, however, Vortex is said to make a good set of strong low rings.

Ammo Suppliers:

Stay away from American Eagle in the black box, if possible. Soft brass getting stuck in the chamber and being difficult to extract has been a commonly reported problem. You’re welcome to try it out for yourself, but please be aware of its issues.

Online suppliers such as Freedom Munitions,, and are all great options.



Easy barrel change for different calibers, indeed.


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  1. It’s good that they are trying to get a .50 caliber weapon into a cheaper package for the everyday shooter, but I see some problems with this. Recoil with a .50 can be pretty rough regardless of the gun, but a 17 pound weapon would not be fun, and if the accuracy is subpar then what would be the point of having a weapon in that caliber.

    • If you are concerned about recoil, just get a suppressor for it. Between the recoil reducing properties of the can’s baffles and the fact that it would probably have to weigh 5 pounds to be durable enough to survive more than three shots, it would probably do a splendid job reducing recoil!

      Disclaimer: I have never shopped for .50 cal suppressors. I have no idea if they are even available … or how ridiculously large they are. What I picture in my mind is bodacious to say the least.

      • AAC has a .50 BMG suppressor. Weight is 4 lbs 15 oz, 15.75″ over all length and 12.65″ when on the gun.

        It’s worth noting that the cost of the suppressor is two and a half times that of the RN50.

    • Judging by the photo, this uses standard AR-15 stocks. So take FAB Defense GL-Shock recoil-reducing stock and put it on it. It has a nice, strong spring, and a cheek riser as a bonus.

    • There’s actually at least Safety Harbor Firearms, Spartan, and if memory serves a few others that build a single-shot .50BMG barrel assy that goes right on an AR platform.

      Will the poodle popper furniture take the hit from the .50? For the hundreds of rounds (or less) that you will likely ever fire from that thing? I’m going to offer it’s possible. Most furniture is orders of magnitude overbuilt, especially stuff that’s current and plastic. You can pretty much run over most butt-stocks with a frakkin’ car and we’re talking about compressive force here.

  2. If you can’t afford a .50 from a company with a good reputation for making them, you can’t afford to shoot .50 in any quantity. People will buy this, fire 3 rounds, and sell it or stuff it away for years.

    • “People will buy this, fire 3 rounds, and sell it or stuff it away for years.”

      A short while back, TTAG posted a picture of .50 BMG ammo on the shelf of a Wal-Mart at $35 for 10 rounds.

      At under a grand for the gun and ammo available local for $3.50 a round, Mark Serbu is gonna sell a lot of these…

    • People will buy this, fire 3 rounds, and … stuff it away for years.

      That is exactly what I actually want to do with such a rifle because I really want a .50 BMG rifle for “just in case” scenarios. And yet I cannot justify spending $7,000 for a rifle that I hopefully never actually have to use.

      That rifle is the perfect balance between price and function when you only want one “just in case” and don’t plan to shoot it regularly.

        • “Just in case” … as in very ugly SHTF scenarios that we all hope and pray never come to pass.

          I would be perfectly happy to sight in that beast and then put 5 rounds through it once every 5 years or so … and hope that I never truly need it.

      • I second the “just in case” for what question above. Do you think you’ll be sniping off someone at 1200 yards? A super grizzly zombie? Or are you thinking more along the lines of just in case you go hunting in Africa?

        Or maybe you meant “just because” and if so, I don’t blame you!

    • As mentioned, Serbu has been making semi-auto and bolt-action .50 BMGs for years now. Reviews and commentary and shooting results, etc, are out there. I’m hoping to review one of these. I think accuracy is the biggest question, as mechanically it’s as simple as it can get.

      • I will hazard a guess, based on reviews of the other Serbu products out there, and my personal experience (limited) with a BFG – there is no better bang for the buck in that caliber.

        Let’s just look at where it could go wrong – the barrel. That’s it, the only trick on that whole gun is the barrel at least as far as accuracy goes. $875 is about what it would cost me to roll my own single-shot in 50 BMG if I buy the barrel. For someone to make me one for under $1K? Save the brain damage, write the check…

  3. “It’s also a simple, lightweight solution.”

    As noted above, it’s gonna hurt you to shoot it.

    Has anyone considered making a stock with a spring shock absorber mechanism of some sort?

    At that price and considering the reports that Wal-Mart is now stocking .50 BMG ammo…

    “Shut up and take my money!”.

    • Goeff PR,

      The problem with a shock absorber stock is that it will enable the scope to smack you in the face and cut your eyebrow. (Ask me how I know.)

      What I would do is simply bring separate weights and attach them to the barrel and/or receiver and let an extra 10 pounds of weight absorb the recoil.

      • “The problem with a shock absorber stock is that it will enable the scope to smack you in the face and cut your eyebrow.”

        For a *rifle* scope, yes.

        Pistol scope, not so much…

        • Several potential solutions with a short-stroke gas-driven piston. If these become a “thing”, I’m sure someone other than me will build it. If they don’t, I will.

        • Goeff PR,

          Yes, a pistol scope has oodles of eye relief. And a pistol scope limits you to something like 2x magnification which is useless if you are trying to put rounds on target at 1500 meters.

        • “a pistol scope limits you to something like 2x magnification”

          A very good point. I am *considering* this as an entry for long-range shooting, so I will need the magnification.

          There must be a rifle scope available with some extended eye relief…

  4. Pic of someone with their RN-50 sporting a Slide Fire stock shows up on the interwebz in 3…2…1…

    I don’t want one but I’m glad someone is doing this. If only Cody would print one…

    • .338 lm supposedly does just as well, and will be less punishing, but cost is about a wash unless you are reloading.

      Disclaimer: I keyboard comando’d all of that.

  5. Sure I’m going to touch off a giant anti materiel round inches from my face… with a rifle from Crazy Eddie’s Discount Emporium.

    I mean what could go wrong?

    Those guys who pay more are suckers, and… ARGH! AIIEEE , MY FACE, MY EYES, MY EYES AND MY FACE… Blurgle blughha bluugh…

    • Mark Serbu has been at this quite a while and even though he does live in Florida, he’s an honest business man as far as I know.

      • Sorry, I’m sure he’s a fine human being… But I continue to believe there are certain purchases where one should not go bargain bin.

        But forget that… “even though he does live in Florida” was totally subtle and hilarious. I’m still chuckling to myself and plan to use that line without attribution every chance I get!

        • I have no idea what kind of human being he is or isn’t (Florida, remember?), I just know that he has a good rep for building and selling firearms… (Florida is a con-man’s haven for a variety of reasons, but there really are some good folks who just enjoy the weather.)

          Seriously, I don’t personally know him, but I’ve shot a couple of his guns, and I’ve read the experience of others who have done the same. AFAIK, it’s overall positive. Though that ‘super shorty’ is just silly.

          I don’t disagree about the ‘discount bin’ philosophy, I just know the cost of this stuff, and if you make the barrel from scratch, you can build a .50 for under a grand like this, and still make a decent margin even doing it right.

        • The parts count in this compared to a semi or even a bolt gun is far, far less. It would be easy to explain the low cost as coming from high simplicity rather than low quality. It almost certainly has fewer potential failure points than semi or bolt actions. I only saw serial number 1 in person, photographed above, and didn’t really examine it closely, but I wouldn’t be so quick to accuse it of being cheap rather than inexpensive…

    • I felt that way touching of my first round of .338 Lapua through my “bargain” Savage 110 BA. And then I was fine.

  6. I’m diggin’ it. I was thinking about something similar and where is might fit in the market. I was thinking more like a single shot bolt action, but that would increase the price. Screw on breech is…interesting.

    I wouldn’t be interested unless the accuracy is there. Recoil, that’s what muzzle brakes are for.

    I think there is a market even if the accuracy isn’t there. iMHO, Two kinds of 50 shooters; those that want to shoot accurately at long range and those that want to crush cinder blocks at 100-200. Obviously those shooter have different accuracy tolerances

  7. It’s the hinge part that I’m missing. I have these same drawings (see doodle) in my notebook. The screw cap loading allows the gun to self headspace. With the break action letting the hammer get out of the way. Now I know how to finish my own 50 bmg project. Back to the drawing board.

    Also simple is good, this gun has a very high potential for accuracy. Floated barrel with what appears to be an ar15 pattern trigger group. Also, as far as recoil goes, its more about the muzzle brake than the wieght of the gun. Besides, we all need a 50bmg sitting in the back of the gun cabinet for a rainy day. Changing calibers would be very easy. New barrel and chamber cap.

  8. I can see buying a .50 with a completely impractical loading scheme… but not for $875. If I’m going to pay that much I might as well pay a little more for a bolt.

    But then again I guess I’m not the target audience since I can’t see myself buying one unless I won the lottery and got to start an arsenal in earnest.

  9. How much more complicated would it be to put an interrupted thread type breech block on it? It’s as big as a cannon, might as well function like one.

    • If I had to guess, two reasons. One, less machine changeover time.

      It’s been a long time since I’ve run a lathe or mill, but you can do the threading for the cap – and a number of other things – with a single session on a good lathe, and probably (in the case of the threading) with standard (e.g. readily available and inexpensive) tooling. Likewise for the cap.

      An interrupted screw is more total time, and changing stations at least once. So, more expensive on both the barrel and breach side.

      Two, safety. A threaded cap will (should) need to be on most if not all of the way before the hinge will close, so you probably can’t inadvertently forget to close the breach properly before firing. The continuous threading, if not all the way down, will still give you considerable strength. For an interrupted thread, depending on the design, there’d be a much greater chance of someone managing to insert the block but not rotate it, and still able to close the hinge. That would likely be a bad day.

      • With an interrupted thread in this case it’s a simple issue to resolve; you merely make it so the firing pin tip sits in a “notch” in the cap, that way if the hammer falls and it’s “out of battery” you hit the cap instead of the firing pin.

  10. A interesting one-off toy but I’d rather pony up more for the bolt action. After all, if I’m trying to disable an MRAP I might need more than one shot to hit the driver.

    Of course, I don’t know how you’d disable an M-1 Abrams…

    • “Of course, I don’t know how you’d disable an M-1 Abrams…”


      A pit trap.

      Good luck finding someone to dig *that* hole…

      • Thermite. As long as you can get close enough to get on top, tanks are easy to disable. Let alone disabling the tracks…

        • Tanks are large, rather immobile, and inherently don’t lend themselves to close quarters battle. Been that way since the beginning of tanks. It is that way even now, and why the tank will eventually disappear from the field of battle.

          You merely need someone who can place a charge on a tank, without them being able to fire a gun, especially when they don’t even know it’s happening. It’s really not that hard.

        • Real simple. Piece of cake. Nothing to it. Tanks just park in isolated areas all by their itty bitties and wait patiently for a hero to waltz up and kaboom them.

          You’re my hero.

  11. I don’t see the point of a gun that has a fire rate less than that of a musket. A bolt action AR upper exists for .50 BMG for $1000 I think. Yeah, you need the lower to use it, but the AR is so popular most people have the lowers already and that single shot bolt action is a lot faster than this.

    As for saving money on a .50 rifle, it’s a laughable concept. If you can’t afford even the .50 upper, you’re never going to afford shooting it either then.


  12. DON’T DO IT!

    Serbu has not been “Manufacturing a bufferless AR for years,” It’s been VAPORWARE! They’ve taken people’s money on preorders and have been promising a deadline for a very long time. I suspect this .50 will be the same. Serbu can’t fulfill the product orders they have, and are worse than Keltec! Don’t get sucked into buying more vaporware, because they still have a product (SU-15) That no one has even seen outside of Shot Show or Serbu HQ.

    DON’T DO IT!

  13. I have a number of concerns about the design of this rifle from the get go.

    1. First major thing wrong is the breech design which is a simple screw on style. This can allow someone to not fully screw on the cap causing excessive head space problems maybe on a random scale. If the hex head rear end had to perfectly align with the lower receiver to close then this would not be an issue. Requiring the hammer to contact the firing pin though a perfectly aligned narrow (ie just wider than the hammer) vertical slot would accomplish the same thing. More threads would be better as well for strength especially if normal 55 degree threads are being used instead of square threads.

    2. This rifle comes without a bipod, butt stock, or scope. Half the people reading this will have a spare carbine stock laying around so the problem is the scope and lack of a bipod which is a $175 add on. Missing a bipod is really a problem because most people do not have the ability to properly benchrest or bag a 50 BMG rifle that only weighs 17 lbs. And no a $60 Harris bipod for a Remington 700 or a $20 no name Chinese gun show special will not work safely. Scopes for spring piston air rifles and 50 BMG are subjected to the same recoil forces but work at very different ranges. Usually one can get by with a lifetime warranty $350-500 hi power scope for a 300 Win Mag bolt action for a while though. $100 Chinese gun show special scopes are likely to be broken or worse dangerous in no time.

    3. No proper hold open when the barrel is opened is a bad idea. This is not a thin cheap 2 lb shotgun barrel that can be cradled over your arm. This is a 16+ lb barrel/scope/maybe bipod attached to a 3 lb receiver which has many pinch points and will self close so this problem needs to be fixed. The most elegant fix would be to have a simple barrel hold open lug operated by the break lever below the lug that closes the action.

    4. Better and full support of the lower receiver (the wave shaped ramp) where it meets the breech cap. Doing this and making the lower receiver out of steel (if it is not currently so) will help in case of a breech cap failure and even in breech cap setback events.

    5. Exposed hammer spur and seemingly no safety is not a good combination. This seems to be a modified AR 15 FCG so adding a safety is easy enough to do. Also doing #4 above will help cover the hammer spur.

    Finally 50 BMG is a different type of gun that requires a special range or a lot of open area to shoot safely. Guys who want to try an inexpensive 50 BMG before buying a much more expensive gun are likely going to be okay. Guys who choose this over another AKM/AR 15 thinking they can shoot cement blocks, 5 gallon pails full of water, and the 25″ console TV that the trash men did not pick up at a local fish and game range are going to be trouble. Also $875 is the show pre order price which will go up to $1199 later this month.

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