RG-037 or 7.62x28mm Cartridge: Soviet Version of the .300 Blackout Concept

RG-037 (a.k.a 7.62x28mm) was an experimental Soviet cartridge developed in 1983. Its parent cartridge is the 5.45x39mm. The RG-037 has similar dimensional relation to 5.45x39mm as the .300 Blackout has to .223 Remington. If you apply the .300 Blackout case forming method to the 5.45x39mm cartridge, then you’ll end up with something similar to the 7.62x28mm. The initial prototypes of this cartridge were probably made by cutting the 5.45x39mm case just below the shoulder (28mm) then necking down the cut case to .311 caliber (with some neck turning).

7.62x28mm with different projectiles

The history of this cartridge begins in 1983 when the Soviet union started “Vintorez” trials to adopt a new integrally suppressed weapon and subsonic ammunition. The designers first experimented with loading 7.62x25mm Tokarev cases with heavier projectiles to make a subsonic round. They shortly understood that this kind of solution didn’t meet the penetration requirements of the trials. They needed a long enough projectile to house a sufficiently large armor-piercing core and at the same time be heavy enough to travel at subsonic speed. The new cartridge also had to be loaded with more powder to propel the large bullet and generate enough pressure to cycle a semi-auto mechanism. So they had to design a new cartridge with greater case capacity than the 7.62x25mm Tokarev had.

This is when the RG-037 was born. It was designed by a man named N.V. Zabelin. The cartridge seemed to satisfy all the requirements and they even started manufacturing it in the Tula Ammunition Plant. However, the minimum penetration requirements for the new weapon/ammunition system were raised even more in 1984, which RG-037 couldn’t meet anymore. That lead to dropping the further development of this cartridge. The successor of RG-037 in the trials was 9x39mm cartridge, which was eventually adopted along with the Vintorez rifle.

One of the trial/experimental versions of VSS Vintorez rifle reportedly chambered in 7.62x28mm.

I think if loaded with modern powders, this cartridge will perform better and it can be reintroduced at least in the countries which armies use 5.45x39mm caliber rifles. Just imagine an AKS-74U (a.k.a Krinkov) rifle chambered in this RG-037 caliber and suppressed. Although, I would rather go with simply necking up the 5.45x39mm case or factory forming the neck to .311 or .308 caliber. Here is what I mean:

The left round in the above image is what could a .311-5.45x39mm cartridge look like. I used Hornady cartridge images to make this mockup because of my “outstanding” (almost non-existent) CAD designing skills.

An AK-74 rifle (or one of its derivatives) chambered in such caliber could get all the benefits that .300 Blackout gives to the AR-15 platform: conversion requiring only a barrel change, effectively suppressed yet powerful subsonic round, same magazine capacity etc.





Hrachya H

I was born and currently live in Armenia, where I work in a family business of leather goods manufacturing. Being a retired sergeant of my country’s armed forces and a lifelong firearms enthusiast, I always enjoy studying firearms design, technology and history. Also my knowledge of Russian allows me to translate and make Russian/Soviet/Combloc small arms related information available for the English speaking audience.
Should you need to contact me, feel free to shoot me a message at TFBHrachyaH@gmail.com


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  • The question is, would it blow up AK-74s like .300 Blackout does AR-15s?

    Great article, Hrachya!

    • noob

      I guess I’ll have to swap the upper on an ak platform rifle and… oh wait

    • Hrachya H

      Thanks ! 🙂

    • Only rounds stupidly loaded with inappropriate projectile profiles and weak neck tension can chamber in 556 rifles. If you blame the cartridge for foolish commercial or handloading decisions, then just about any cartridge is liable to the same criticism.

  • Get over it Fanbois

    Since most former Soviet Union nations loath Russia. They won’t ever adopt another Soviet round. The only reason 5.45mm Tavors and CZ 805s/806 even exist is to use up old USSR stocks before adopting NATO rounds or use for SOF units.

    Russia themselves won’t adopt such a round as 9x39mm is just that much better. Their military seems to want to beyond the AK-74 to something more fitting.

  • Koh

    There is utterly ZERO need for this cartridge. Just bring the 9x39mm to the USA.

    • iksnilol

      You can just make it in the US. x39 cases and 9.3mm bullets exist in the US, no?

      • mig1nc

        Indeed, Midway lists many .366″ projectiles. Even TSX types. They probably aren’t designed to expand subsonic though. At least that’s my guess. I don’t really know.

        • iksnilol

          Yeah, I’d think a safe bet would be to go with lead bullets. Cast lead bullets, moly coated (to avoid fouling).

          the TSX types need to go faster than the speed of sound to expand properly.

  • Poresz Poreszovics Poreszov

    Is the projectile the same as the 7.62×39mm’s one?

    • .45

      Judging by the second picture, not even remotely. Looks like they made it maybe twice as long or so, but varied the thickness while experimenting. Hard to say exactly from a glance, but certainly not the same.

  • .45

    My first thought: Why not just modify the 7.62×39 cartridge since it is closer to what they needed anyway?

    Second thought: Oh yeah, that’s what they did do, with the 9×39.

    I’m a little slow sometimes…

    • Sledgecrowbar

      Really they could just load a heavy bullet into a standard x39 case to make a subsonic round similar to Blackout. Paint the tip to specify and run it in a suppressed AK with the gas tap sized and shortened if need be to match the powder charge.

      • .45

        Exactly what I first thought, but going with the 9×39 probably helps prevent kabooms, so even if it didn’t do anything to change the effectiveness, it would be worth it.

  • Threethreeight

    300BLK AKs are already a thing though? No need to revive some dead cartridge.

  • Richard Douglas

    Yeah…this seems like a lot of work to get where handloading a 200+ grain bullet in the 7.62×39 would get you to. A nice hardcast round nose .303 bullet will get you 220 grains, and even though you have to seat it deep, you want less powder capacity anyway…seems like a question that didn’t need to be answered honestly.

    • MSG1000

      I’d assume 7.62x39mm is a heavier carteidge than it needs to be. It’s much fatter than the 5.56 or the 5.45, doing this way would save weight. That said, you’d prevent confusion and save loads of money if you used the 7.62×39.

    • JoelC

      The problem then is trying to get it to cycle properly.

      I do wish 9×39 became a thing here in the USA, though.

    • Rap Scallion

      See……..I told ya so!

  • Alexandru Ianu

    Why couldn’t they just use a more 54r like projectile in the Tokarev? You can get 220-240 grains and if the taper at the rear isn’t too long, there’s enough capacity to get 1000-1100 fps, which is optimal for subsonics (and identical to .300 Blk).

    In fact, during the cheap-and-plentiful-surplus faze of the 7.62x25mm, this was actually done paired with a Tokarev AR upper and regular STANAG lower. The long rounds fed from 5.56 magazines just fine. I think the wildcat is called Tokarev Whisper.

  • Retriever222

    I’d just like 9×39…

  • ActionPhysicalMan

    Damn, Trump was selling our best secrets even back then;-)

  • Seth Hill

    “I would rather go with simply necking up the 5.45x39mm case or factory forming the neck to .311 or .308 caliber”

    Ummm…..if you are loading these yourself, wouldn’t it just make sense, and be easier, to take 7.62×39 cases and use a lighter load with a heavier bullet to get subsonic?

  • Rap Scallion

    I guess, because I am 76 yo, I sit back and look at all of this wheel reinvention with a certain amount of humor! I am not that old…….. like to remember invention of gun powder, but I certainly do remember the endless cycles of gun and caliber reinvention. It seems to me that when ever we get a slack point in weapons evolution, we redesignate, or attempt to redesign an already working particular weapons platform, we try and reinvent it and that usually results in a caliber/cartridge reinvention. Some of it is normal progression, and some of it is just pure gun writers/inventors BS to stay in the lime light, and stay somewhat relevant to the current conversation. Say the ’03 Springfield 30-03/30-06, improved o the Springfield 1898 Krag 30-40, and the M1 Garand improved and moved on up the weapons chain…..I get it! But the current phase of the wheel reinvention is really getting both bizarre and humorous…..we seem to now have a small caliber weapon, that is a semi-good military rifle in certain situations, and we now want it to shoot all manner of weights and size configurations of bullet combinations. An all purpose rifle to fit all niches of armed combat….AND ALSO nust become the basis of all hunting, sport shooting, home defense, and “Ya just gotta have one of these” rifles! Now it seems, that we haven’t been alone in this endeavor, it turns out, in a parallel universe, we have got the Russians doing it too! ALL of this AR Platform reinvention proves we have nothing left in the imagination tank!