The New CZ Bren 3: What Did They Change?

From the Mauser bolt action to the AK and AR, all new military rifles take time to perfect. With the Bren 3, CZ is now on the third iteration of the Bren platform, having gone from the original 805 to the much-improved Bren 2 and now a collection of less obvious changes to create the Bren 3. These changes have been directed by combat use of the rifle in Ukraine as well as the lessons of mass production. The main changes are around durability, taking a good system and making it better – along with a few changes to improve the modularity of the rifle. Specifically:

– Gas settings changed from Off/Normal/Adverse to Suppressed/Normal/Adverse
– New removable hand guard, including rail, Mlok, and UBGL versions
– Strengthened stock attachment
– Heavier barrel
– Replaceable cam lug rail in the receiver
– 7.62×39 chambering replaced by .300 Blackout
– Optional folding charging handle
– Slightly improved stock, and universal compatibility with collapsing “PDW” stock
– Heavier barrel
– Strengthening of various small internal parts

The handling of the rifle has been left essentially unchanged, and the grip/magwell assembly is interchangeable with the Bren 2 (although virtually no other parts are). The Bren 3 is only offered as a select-fire rifle for military and police customers for now, although I am sure a semiautomatic civilian version will be coming sooner or later.

Special thanks to Helitom (https://www.helitom.cz), B-Rdy (https://b-rdy.cz), and Hard Task Training (https://www.hardtask.cz) for making the helicopter shoot possible!

28 Comments

  1. Re: “7.62×39 chambering replaced by .300 Blackout”
    Potential users should be aware that this is a change to a cartridge with less kinetic energy. A terrorists AKM has more punch than the typical police officers .300 BLK arm. And it cannot be changed, because the available space for propellant in the .300 BLK cartridge is considerably smaller.

    • Probably chosen so as to reduce the number of lower receiver types in production… 7.62X39 needs a longer mag well.

      My guess is that the 5.56mm chassis will remain what it is, and if they need 7.62X39, then it will be done on the bigger platform for 7.62 NATO.

    • Would someone explain to me the love affair with .300 Blackout? What are the pros and cons.

      It seems ok for competition shooting, but I don’t see its usefulness for hunting or actual combat.

      • You’ve probably seen Eon’s excellent writeups on the M-1 Carbine: the Army recognized that – while a pistol can be marginally effective in expert hands – the support troops issued only pistols are those least likely to be selected or trained for smallarms expertise, leaving them practically defenseless; and introduced a weapon that practically obsoleted SMGs overnight.

        The Carbine never completely replaced pistols or even SMGs; it’s still three feet long, and it isn’t great for suppression. My .300BLK PDW offers Carbine ballistics (but with more streamlined bullets, better mags, better cartridge support, etc.) while in the stowed position it’s hands-free holsterable at less than half the Carbine’s length. If I want to shoot suppressed it turns into a .45 Super with a simple magazine change.

        • Okay, if we are in PDW land with this ammo, what sort of PDW do you have that uses .300BLK? How does the terminal performance and effective range compare to commonly used PDW ammunition?

          • CMMG Dissent upper on a Form 1 lower. Effective range roughly equal to Carbine’s 300m (or greater, given optics and better-BC projos). Terminal effect should be much greater than “commonly used PDW ammunition” if you mean 4.6 and 5.7 with .380-equivalent ME.

      • From the operational/strategic level, I’m not at all a believer in the entire “PDW” concept, except for very limited use for instances like aircrew.

        The big problem you have to address is the one where you have to recognize that there really aren’t any linear battlefields such that you can get away with separating “real combat guys” from “everyone else”. Everybody in a uniform is a combatant, and has to be able to go full-spectrum on a moment’s notice. Witness what the hell happened to the Russians in Kursk; one day, there they are, sitting fat and happy without a care in the world. Then, shockn’awe, here’s the enemy and we’re no longer able to count on our being in a combat backwater. Same thing happened to them on the deathride into Kyiv; “Oh, we’re behind the enemy lines where the combat troops are, and we’re safe enough that we can operate like it’s a peacetime exercise…”

        Yeah, how’d that work out for them? And, it’s only going to get worse. Competent enemies are not going to leave you with a comfortably linear battlefield. You will note that Wagner is currently taking it up the fundament in Africa from Ukrainian operatives, who’re going after them there. Linear battlefield, my ass…

        And, that being the case, we’re on to the other implication of all this: You cannot have multi-tier armies, where you have delineation between combat troops and “everyone else”. “Everyone else” is where the fight is going to go, inevitably. Hell, it may go there and actively avoid the “really real combat troops” entirely… That was the lesson we should have taken from Iraq and Afghanistan, ourselves.

        Going forward, if you wear a uniform? You need to be trained and equipped to put up a credible portrayal of front-line infantry, or you’re going to be on the losing side. I don’t know how many opportunities we missed in Iraq and Afghanistan because the logistics troops weren’t willing to take the fight to the enemy at every opportunity, particularly when they represented about 90% of the actual contacts we were getting.

        The Russians are learning the hard way about the reality of modern warfare, which is ironic as hell since they pioneered this all-aspects threat environment fighting the Germans during WWII. You want to see the reality of things, go trace out the history of rear-area battle that the Germans had to learn to counter; it’s been a factor since WWII, even though we studiously ignored it.

        The unpleasant fact of this, in reference to PDW weapons, is that you cannot have two-tier forces: Everyone needs to be able to do infantry when infantry is required. That means “Everybody’s a rifleman”, and that has to actually mean something. All the troops need the training, the mentality, and the equipment to do the job when it arises. You cannot have forces that say “Oh, combat ain’t our job… Call the Infantry battalion over there…”

        At the very least, you have to do what the Germans did in WWII, and mandate that the logistics weenies keep the people shooting at them fixed in place until actual combat troops get there to finish them off. That’s the only way you deal with this crap, other than allowing yourself and your forces to be nibbled to death by ducks.

        So… No PDW. Only rifle/MG/mortar, just like the grunts get, along with their links into the fire support network. That was the lesson of WWII rear-area battle, and it’s just as relevant as today. Train everyone as basic infantry, and inculcate the combativeness to ensure that they at least maintain contact and pressure on the enemy until their peers in the actual combat arms can come deal with them.

        • PDWs should never have been anywhere near the front lines. If they were this was a big mistake. But I do think there is a role for them in the troops way behind the lines or general security around bases. Away from the front lines, there always will be scavengers to deal with. This is where something with more punch than a pistol, yet not as bulky as a rifle has a place.

          • Bart, the point is that there are no areas of “lesser threat”, and that you have to be able to go toe-to-toe with the enemy everywhere. If you aren’t, well… You’re going to have your so-called “rear-area” troops nickeled and dimed to death, and you’re also going to miss out on opportunities to engage the enemy.

            This crap was all worked out the hard way by the Germans during WWII. The only thing is, nobody after the war wanted to pay attention to it or deal with the implications. There are no “safer areas” where you can afford to have second-tier troops; they should either be capable of doing what the line troops do, or they should be civilians. Period.

  2. @ Kirk
    Nope, it does not need a longer mag well. You only need to extract the insert for STANAG magazine – otherwise the lower stays the same on Bren 2, which had the 7,62×39 capability. And – as Ian said, and I concur, having handling it as well – the lowers are identical, just control levers were tweaked a bit, but are completely interchangeable. The magazine well is retained unchanged – note the STANAG magazine insert present in the magwell. According to what I was *told* (relata refero – do not shoot me if that proves not true ultimately), the initial B3 is to use the B2-style lower until these run out, and then the new lower would be introduced, only taking the STANAG magazine.

    • Leszek, if you pause to think about what I wrote, then this is fully in line with it:

      “According to what I was *told* (relata refero – do not shoot me if that proves not true ultimately), the initial B3 is to use the B2-style lower until these run out, and then the new lower would be introduced, only taking the STANAG magazine.”

      All they’re doing is running through the stock of B2 lowers, and once they’ve done that, then precisely what I said is what is happening. 7.62X39 is being phased out, and they’re not going to make any more lowers that can take the longer cartridge.

      Legacy technology rears its ugly head, once again. The 5.56X45 cartridge wasn’t an optimal choice when it was made, and the constraints forced on later generations of weapons by it are tying people’s hands decades later. Not that different from the issues brought in by the Lebel cartridge choices, actually…

      I still think a clean-sheet cartridge and rifle would be a great idea, along with a clean-sheet cartridge and MG would be for the support MG role. Where we’re at is trapped in the sub-optimal world where the individual weapon cartridge is just a little too light, and the support MG cartridge, having been compromised by the clearly insane need to have it work in an individual weapon as well, is also compromised. Both are “good enough” for now, but at some damn point, I rather hope someone pulls their collective heads out of their asses and says “Yeah, we know how to do this, we just need to do it…”

      NGSW ain’t it. That whole damn program was just a recap of the same flawed process that created the 7.62 NATO fiasco, and it’s going to have the same result. My money is on the infantry rifle version becoming a de facto DMR weapon, and the units out in the field raiding their supporting branches for all the M4s they can steal… The root of the problem is that the NGSW just doesn’t answer the mail for an individual weapon, and the damn things are just too big, too heavy, and the ammo loadout just isn’t big enough for how we fight.

      The real issue with all too many of our military programs is that the developers and the leadership just turn the reality distortion knob up to about 11 or 12, and leave it up to the poor bastard out at the tip of the spear to make it all work. When that blows up, as it inevitably does, then they throw together some half-ass solution that winds up holding the line for decades… Which, if you recall, is precisely how the US wound up with the “interim” M16 as its longest-running service rifle. Ever.

      Idjits. The world is run by them, and what does it say for us that we allow it?

      • Within the STANAG constraints, there are still good options that could have been adopted. Not the 300 Blackout (Whisper) which is really an excellent niche subsonic cartridge. What about 6.5 Grendel or 6.8 SPC? Maybe they are or aren’t “better enough” to eclipse the 5.56 NATO, but they have the punch of the 7.62×39 along with better retained energy at 300 m…and could be had for the price of barrel, bolt head and magazine (and possibly buffer+spring) changes.

        • The original intent for the AR-10/15 family was that they’d have pre-loaded disposable magazines… Which was why they had that nice long magwell to stabilize and support the disposable magazine. One reason, at least…

          That magwell has constrained things, ever since. I like the easy insertion and handling it allows for, but I loathe the weak-ass feed lips and magazine body that it mandates. The choices made back in the 1950s under entirely erroneous considerations create problems to this day… Until Magpul and better materials finally fixed the issues, the magazines were always the weakest link in the platform. And, because some idiots decided to try and make them the NATO standard… Sweet babblin’ baby Jesus, but we have had some issues with all that.

          The thing is, to my mind? I can’t really say, with mathematical precision and certainty, that the 5.56mm is at all inadequate. I feel like it is, but lacking the data that nobody has bothered to go out and collect in the real world, I would have one hell of a hard time justifying making the change. I still think it’s on the ragged edge of “not enough oomph”, but as I say, that’s unscientific and due to personal belief I couldn’t possibly quantify or justify to save my life.

          Subjectively, were I designing a new individual weapon cartridge? I’d go out and take something like 6.5 Swedish, download that bugger until it was controllable by about 90% of the average soldier population, then “right size” the cartridge case to fit the resulting powder load, and move on from there with a conventional rifle platform. From there, you could likely work out a bunch of very nice, very easily managed cartridge variations to make the individual weapon work. On the support MG side of things? I’d begin with the Swedish MG cartridge they issued for years, figure out what I could do to make that effective out to about 2100m from a tripod, and leave it at that. Between those two, I think whatever army that procured it would be well-served by those weapons for a long time. The idiocy of the high-velocity “Pierce the non-existent body armor of the Russian infantry” NGSW cartridge is just… Nuts. If you’re burning out your barrels with a scant few thousand rounds, then you’d better be putting quick-change barrels on your individual weapon, and calling it good. Which they haven’t done, by the way… I doubt that those high-velocity variants will ever see issue, either. Mainly because the body armor issue is a fantasy, and the cost is going to be murderous.

          • The really nutso thing about the NGSW cartridge is that they didn’t even get particularly high velocity from that super-high pressure: not much more than a .30-06 delivers. That’s because they use a short barrel, likely in imitation of the M4. The combination of short barrel and high pressure inflicts serious hearing damage, which then requires a silencer, which lengthens the rifle to where the short barrel gives no handling benefit, plus adds even more weight than a longer barrel would.

          • I kind of like one of the proposals made by the ex-Mauser Germans working for Franco in Spain who developed the CETME and its radical cartridge. When Spain was giving in to the pressure for NATO standardization, Volgrimmer (I think) tried to save their work by proposing 2 different 7.62X51 loadings, a heavy bullet that would be issued with machine guns, and a light low-power plastic-cored bullet to be issued with CETMEs, but each round capable of emergency use with the other gun. This preserved the advantages of the original CETME round for rifles.

          • I dunno… I feel like the light-load 7.62X51 was still a bad concept, in that you’d still have to make all that brass and haul around that excess weight for the case.

            I think the one true path is basically a dual-caliber solution all the way down into the squad. That’s what the “desire path” has shown since WWII and the German StG44/MG42 pairing, and it holds true to this day.

            I lay you long odds that if you were to offer up an “arms room” solution such that the troops could tailor what they carried for each mission, then you’d soon find that they gravitated towards carbines like the M4, and machineguns like the PK. It just works…

            You have to have a handy little rifle that you can make snap-shots with, and will be easy to carry and manipulate. That ain’t the NGSW individual weapon… It is the M4. You also need to have a heavier support weapon that can gnaw through light cover and not be deflected by impedimentia like tree branches and leaves, which ain’t the 5.56X45. I’d argue that while both of the common NATO calibers are adequate, they’re sure as hell not ideal, and that no fantasy-land “one cartridge to rule them all” is ever going to be workable.

            You have to go into this with an open mind, and actually examine what the hell is going on during today’s firefights. If you’re going to need a MG in support, then you need it to be in a cartridge that can actually achieve effect out to around 1500m, minimum. And, by “effect”? I mean that said cartridge has to be able to do what old-school full-power rifle/MG cartridges did in terms of material and personnel damage out to 1500m, minimum. Ideally? 2100m

          • Kirk, brass wise, seems like logical next step in ammo evolution was always known – caseless,
            yet its baffling why, seeing HKs space magic, 35 years afterwards we have nothing near it, why all development stopped ?

          • @Storm,

            Oh, I dunno… Maybe because the technology to actually do caseless isn’t there?

            The Germans with HK and the Defense Ministry said they’d perfected it; the Germans who were out in the trenches and doing the testing? They said “Oh, hell no… It doesn’t work.” The alacrity with which they dropped the G11 is telling; as soon as they could, they did. And, it ain’t come back, sooooo…

            Then there was the US development of it, which was bought lock, stock, and barrel by the silly bastards who believed HK. Turns out, not so much, and they never managed to get it to work, either.

            The root problem is the materials; we don’t have anything that can seal the chamber and last, and the propellants are all seriously high-risk when they can’t be stored in climate-controlled facilities. The guys who were involved in the ACR program all had interesting things to say about the G11, when I got to talk to them. That was about the least-favorite of all the contenders, for multiple reasons.

            Caseless is like nuclear fusion; you can see it on the technological horizon, but the things we need to be able to do in order to make the idea work are simply beyond us at this time.

            I suspect that will remain the case for a long, long time. The big problem is going to be the temperatures produced by the propellant, and the fact that the seals on the chambers just aren’t up to the job. Sadly, brass cases will probably be with us for a long time to come.

            You’ve also got the problems with chemical stability that may never be overcome; the big issue I heard complaints about was how weird that Octol compound behaved after it was stored in high-temperature areas like you’d find in a typical ammo point in the desert.

          • I think youre on a right track, good analysis.

            Heh, tbh I’m not that big of a fan, but one of my favorite action movies from first half of 1990s (in top 3,4) “Demolition Man”, (even) had G11 in it!
            Around movies release, it was still a time when probably general (gun nut) public thought the rifle is just around the corner, specialists probably knew its d.o.a. and only briefly reserved for science fiction – museum of the past!

          • @Storm,

            I gotta be absolutely honest with you, in that my opinion is that if we’d somehow never developed cartridge case weapons, going along the original track of the various early ideas like the Dreyse and the Rocket Ball concepts… We’d probably have gotten around to the cartridge case by now, and it’d be the “coming thing” for all of its advantages.

            You get down to it, and start thinking about the various issues you’d have with caseless, and it really starts to look like a “less than good” idea. For one thing, that propellant block being out there hanging, with no protection? Uh… Yeah, sure, I’d love to have a couple of pounds of low explosive hanging out on my web gear with me in combat… Especially in situations where I need to worry about flash fires and things like sympathetic detonation. Then, there’s the storage issues: You can actually set fire to cartridge-case ammo, and it won’t go “bang” right away. Try that with Octol, please; see what happens. One of the guys I know who was involved with the ACR program testing snaffled up some of the caseless ammo that got damaged in handling, and wanted to see for himself what happened when you set fire to it, just to see what it was like.

            Was not one of his smartest moves, he later admitted. Apparently, broken pieces of Octol and a lighter are not two things you want to mix, unless you want some nice flash burns.

            I remain highly skeptical of the entire premise of caseless, to be quite honest. I want my energetic chemical compounds carefully protected by purpose-built little containers that remain inert and safe until I want them fired, and that doesn’t include most of the caseless ideas I’ve seen.

            Although, it would be kinda pretty, watching the fireworks if we could persuade the enemy to adopt the technology…

            Whole thing just isn’t thought through, in my humble opinion. By the time you get done factoring everything in, like handling and safety concerns, I think you’d almost come around full circle back to the cartridge case, once you’d addressed everything.

            I’m also rather dubious of the proposition of dealing with chain-fires in the magazines. From what my informant told me about the results of lighting a single propellant block, I have to extrapolate out to what would likely result from an entire magazine going fwoooosh!! in your weapon while you were carrying it. Worst-case, body-slung and hard to get off you…

  3. We should see a semi-interesting ‘special announcement’ from CZ come SHOT Show 2025. Circling 1/21/2025 on my calendar. Anyone want to take bets? (It is Vegas after all.)

  4. The non-existent body armor of the Russian infantry do exist, it is not in general use: https://www.youtube.com/watch?v=io3SPIN0S1k (Russian vs. American Military Armor… Who Will Win WW3???).The interdynamic 4.5×26 mm Rimfire cartrige is better than FN 5.7×28mm, but 5.7×28mm was already not accepted because of it preformace against level 4 body armor. The 6 mm Unified Russian round is ballistic equivalent of 243 Winchester. The 243 is 308 Winchester necked-down to 6 mm. For 0.308 you need to go to heavier bullet to get same ballistic coefficient as 7mm (180gr vs.140 gr). The case is about 30 % of total catridge weight. I do not see that rifle catridge will improve drastically. The most efficient way to improve is to fire a bullet with a better ballistic coefficient at a hight pessure.I do not think plastic core bullets will work on body amor.

    • As we’ve seen from practical demonstration in Ukraine, odds that all that high-speed/low-drag Russian body armor actually makes it out to the troops are very slim indeed. Most of it would likely never be made or procured, with substitute-standard Chinese airsoft gear being what gets into the hands of the troops. The corruption in Russian military affairs cannot be underestimated or really even comprehended. You can get on X/Twitter or YouTube, and see voluminous examples of what the Ukrainians have actually captured, as well as the usual plaintive wails of the Russian Federation troops complaining about the low quality of the gear they’re buying.

      As well, I’m not convinced that the heavy body armor is all that big a deal. My take on it, as someone who actually had to wear that crap in-theater over in Iraq is that if it came down to a peer-level conflict, it’d be a damn toss-up as to which factor killed more troops: Heat exhaustion and general fatigue from carrying all that damn weight, or enemy fire. I don’t think the body armor is all that big a deal; if the enemy has it, then you really don’t even need to shoot the poor bastards: Just get them to run in it, and watch them drop dead.

      I think that’s one reason you see all those apathetic dying Russian soldiers in the FPV videos that are laying around: They’re literally dying of exhaustion and stress, probably after having been chased all over hell’s creation by those goddamn buzzing little banshees. I think that’s a TTP that the Ukrainians aren’t really putting on display, as well… One, because it’s horribly unromantic and not at all photogenic, and two, because it isn’t a look they want to broadcast to the world. You show your FPV guys effectively “playing” with the poor stupid bastards they’re killing, and a lot of sympathy for the Russian troops is gonna develop. Eventually.

      Body armor isn’t a panacea, at all. I’m not even sure we’re going to be using all that much of it, going forward, because once you start doing the tactical cost/benefit analysis, the numbers don’t favor the heavily armored. As well, body armor doesn’t do squat about blast/overpressure, or having all your unarmored extremities turned into bloody sieves via the application of tiny fragments from grenades and other munitions.

      So, this fantasy about NGSW being “necessary” because “Russian super-body armor”? I ain’t buying it, and neither should anyone else. The Ukrainians are actually dealing with it, and don’t see it as much of a major problem; they’re certainly happy enough with the current fleet of small arms, and I’ve heard zero complaints from anyone over there about not being able to “put down” Russian soldiers with small arms fire.

    • “(…)fire a bullet with a better ballistic coefficient at a hight pessure(…)”
      This is odd criticism w.r.t 6×49 cartridge as according to https://www.thefirearmblog.com/blog/2016/08/21/modern-intermediate-full-power-calibers-019-russian-6x49mm-unified/
      because of its heavy propellant charge relative to its small 6mm bore, the round produced incredible barrel wear to go along with its incredible ballistics. and a supersonic range of 1,150m, a full 50% longer than normal .30 caliber full-power rounds.
      Which raise questions how much pressure and supersonic range would be enough for you?

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