Riverman Gun Works Modular Breakdown Rifle

Riverman Gun Works has introduced their Modular Breakdown Rifle or MBR. The MBR is based on a traditional AR upper receiver, adding a charging handle on the left-hand side and removing the gas tube. Further, it adds a special handguard that can be easily twisted on and off.


Factory Description:

With an eye towards versatility, and an aim for precision, Riverman Gun Works introduces the new MBR™ series rifle. Built on the time tested AR platform, the Riverman MBR™ combines the look and feel of an AR with the lethal accuracy of a long range rifle. With a quick change of the barrel, the operator can seamlessly transition to a variety of calibers or barrel lengths to meet the needs of any application. All of this, while still providing the customization capabilities of the AR platform that you have come to know and love. With two variations, the MBR™ is built to serve as a ready to go, do it all rifle. Made with the highest quality parts and built and assembled in the USA, The MBR™ is trademarked and patent pending.


The MBR™ comes on two separate platforms, the MBR-15 and the MBR-10:


MBR is Trademarked and Patent Pending

Riverman claims the rifle maintains zero across barrel changes and shows the video to prove it. 


Check out Riverman by hitting the link here.

Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • Anonymoose

    Maybe I’m just old fashioned, but I should like to think that a 20″ or 22″ would be ballistically better for the .243, 7mm, .260, and 6.5 Creedmoor. On the other hand, maybe they should have just standardized all the MBR-10 barrels at 20″, with 16″ .308 and 7mm barrels for heavy CQB/scout-type applications. I’m sure someone will be along soon to tell me that ALL rifle cartridges TOTALLY reach their full potential out of some stubby 13″ SBR and anything over that is going to decelerate the bullet, or something.

    • iksnilol

      Lapua makes a load optimized for 13 inch barrels in 308.

      I prefer 60 cm barrels in 308, 50 if I want to go short.

    • gunsandrockets

      One practical reason for such short barrels is shorter length in the broken down configuration. But I think longer barrels should also be available.

    • dan citizen

      ALL rifle cartridges TOTALLY reach their full potential out of some stubby 13″ SBR and anything over that is going to decelerate the bullet.

      Everyone knows that anything over 14″ keyholes, and anything over 15″ you can stop the bullet with a thumb placed over the bore.

  • Dracon1201

    Guys… it’s MBR, not MDR…

    • Codie


  • Asdf

    Without a gas tube, how are they making the gun cycle? Did they redesign the bolt and carrier to make it delayed blow back or something?

    • Asdf

      Oh, they just made a blot action rifle out of it.

      • FightFireJay

        Very delayed blow back, doesn’t even open until the bolt handle is touched by the shooter.

        (Sorry, couldn’t help myself.)

  • JumpIf NotZero

    Lol, bolt action feeding from staggered stacked AR mags. That’s too funny. I suppose it is immoral to allow a fool to keep his money.

    • Graham2

      Quote, ‘Lol, bolt action feeding from staggered stacked AR mags. That’s too funny.’

      Why is that funny and why do you think it wouldn’t work?

  • Joe Danger

    You know, I would’ve been all over this upper if it was actually semi-auto instead of bolt-action and wasn’t $2000+.

    • noguncontrol

      agree! before i read the article, i thought, hey another modular AR! yeah!! but then it turned out to be a bolt action. meh.

  • Codie


  • dan citizen

    Ok, so it’s a straight pull bolt action… No buffer needed….

    Why didn’t they just bullpup it, make it 26″ overall, and skip the break down feature?

    • gunsandrockets

      Well a break down rifle has two advantages over the bullpup you favor: easy change of barrel to different calibers, shorter length when broken down.

      • dan citizen

        Two excellent points

        • Iggy

          So what they really should have done is a bull-pup, straight pull, break down.

  • patrickiv

    So is it just friction keeping the rail screwed on? What happens if you bump the bipod? I assume the threads are just timed so that the rail lines up correctly. I mean it is impressive that it holds zero but I would expect some kind of detent or positive locking and indexing.

    • FightFireJay

      My guess is that the barrel nut is separate and is torqued down on the initial install. Then the handguard is attached and tightened down onto the barrel nut and it now also acts as the wrench.

      Like you, I wonder how it gets enough torque and what’s to hold it in place. My only thought is that there is something akin to a lock washer or wave washer assisting in keeping things from moving.

  • gunsandrockets

    Pretty slick. Good for them.

  • Southpaw89

    HA, left hand bolt action AR, a rifle that appeals to 10% of 10% of the population, sorry, if I’m going to save that long for a modular left handed straight pull I’ll just wait a little longer and buy a Blaser. Not trying to discourage manufacturers from trying new things here, but an AR can already be broken down into a fairly small package, I have severe doubts that this will be commercially viable.

    • FightFireJay

      Not that short. And certainly not with the ability to quick change calibers.