The FK Brno is a take on the classic CZ75 pistol made in the Czech Republic. It was originally released as a boutique steel-framed gun, and then later as a much more affordable polymer-framed model. I have one of those polymer framed ones, with barrels for both 10mm Auto and the unique 7.5mm FK cartridge designed for this pistol. I decided to use the 7.5mm barrel for the BUG Match today, which is a 95gr bullet moving at 1800 fps. It should definitely knock down steel…if it can run long enough to get there.
Note that I am in “Big 5” division, for pistols too large to be considered “backup guns”. The rules for this division dictate magazines loaded to only 5 rounds.
7.5 was the proper choice to test out, since few people have experience with it. So does the gun suck or the ammo suck or both suck?
In those case usually is the magazine that sucks.
Wow!, I have the full size and it’s been 100% reliable. I hope the 100 mm is better in the compact version.
Which ammunition are you using? When was the pistol manufactured?
I have one. Great gun. The 5.7 is a phenomenal round based on the 10mm magnum case (they say it’s not but a cross section says it is). Excellent for hog hunting
Do you have the full size or compact version? Also, which ammunition are you using?
Surprised they let you use that on the steel targets. Most subgun matches don’t allow 7.62×25 because the targets get beat up too much.
I have not seen a review of the 7.5 FK Brno have any problems except with you in a match, was this a magazine problem or a bad batch of ammo? Kudos for trying the beast in the match.
Paul Harrell had his own problems with ammo quality.
https://www.youtube.com/watch?v=pRIIXj_wdH8
I HAD a FK Brno PSD and it was useless in 7.5 Brno caliber. Blown primers would plug firing pin hole and until you cleared it, it would have FTF. That happened every 3 or 4 shots. Also had 9mm and 10mm conversions for it. Worked perfectly in those calibers. 9mm recoil was like 22. Traded my PSD model for the Field model and it works great. Its a shame its 4 time the cost of the PSD. Yes, in 7.5 Brno caliber, the Field model still get the occasional blown primer, but Field model keeps working and you don’t know a primer blew until you see empty case or when cleaning you see the small piece of primer in the firing pin hole. The factory ammo is very high pressure and the primers just can’t handle it. Maybe if you could reload slightly lower pressure, it would be a good cartridge. But the appeal of factory ammo is getting almost 2,000 FPS out of a 6″ barrel handgun. By the way, The US reps for FK Brno were exceptional in customer service when I was working to solve this issue.
That’s interesting to know, because I have no experience with these. Most previous reviews I saw were gushy.
My 6″ barrel .357SIG handgun (now a Form 1 SBR) gets 2000+fps with 90gr, all the way up to 2548 for light loads, without any of those issues and without being expensive or scarce. Recoil is light, extremely so with those light bullets.
I am skeptical of the “gushy” reviews on any product. As Kevin noted, and Ian found out, and what I have seen in more calm reviews, there can be big problems with ammo quality consistency.
The round is pretty awesome, when it works. I just don’t see too many people willing to spend a ton of money to test out combinations of guns and ammo to find the sweet spot for the ammo to gain wide popularity. If all the kinks were worked out, I only see niche applications for it. And as you note Mike, there are existing proven and cheaper existing alternatives for these applications
Excellent points! Even if someone wanted to experiment, the options are very limited. While .357, 10mm, etc. fit in conventional magazines, I’m not aware of any outside the originals that accommodate a 7.62×25 length, 10mm case head cartridge. Likewise for .308 barrel blanks with the right twist.
It’s always a gamble when a manufacturer keeps a niche product proprietary. On one hand he’s cornered the market; on the other, unless the product leaves everything else in the dust, the market can stay extremely limited.
The more powerful the cartridge, the harder it is to get the balance between ammo and gun correct, particularly in semi-auto mode.
While the selection of ammo is limited, and expensive, Ian has the resources to do a full test of what is available. I would trust his judgment on the matter.
I eagerly await his 10mm test. This ammunition is tested and reliable. So issues then would be the gun.
Interesting comments here https://www.snipershide.com/shooting/threads/7-5-fk-brno.7126086/#post-11054206
@Bart, who said:
“The more powerful the cartridge, the harder it is to get the balance between ammo and gun correct, particularly in semi-auto mode.”
Truer words have rarely been articulated.
Materials technology is simply not here yet, for these high pressures to actually, y’know… Work.
NGSW, I’m looking at you.
I don’t care what weapon you put the cartridge in, the pressures are high enough to produce blown primers on even a semi-consistent basis? That weapon/cartridge combination is over-pressured, period.
I’m also highly dubious about the proposition that a handgun needs that kind of pressure/velocity. Number one, you’re not ever going to one-shot anything with a handgun; even with a rifle, odds are not good. That being the case, you’re way better off going for multiple hits with something that works reliably and which you can control.
I don’t know what materials technology we need to make primers and cases that can work in this pressure range; I’m not even certain that you can make these cartridges work with the primer technology we use. Maybe what these things need is a steel case that has no primer pocket and is fired electrically? I’m not sure that anything susceptible to a hit from a conventional firing pin is ever going to be capable of dealing with these pressures.
I’ve been sceptical of these high-pressure cartridges since they started being blown up in the press; past experience would suggest that anything that has the typical gun-press weirdo excited is to be approached with extreme cynicism and doubt. What have they gotten right, in the last seventy years? Remember the BREN-10 fiasco? .40 S&W?
If someone’s obviously touting something, then someone is likely to have been paid off or is demonstrating yet another example wherein they’re exhibiting seriously poor judgment. Pay attention to source track records, folks… That’s all I’m saying.
@Kirk
Looking at the stats on the round
https://en.wikipedia.org/wiki/7.5_FK
I’m seeing the 7.5x27mm as basically a pistol cartridge with 7.62x33mm (.30 USC) ballistics.
So far, all attempts to create a handgun firing .30 USC (S&W M10 during WW2, Kimball automatic 1950s, Automag III 1980s) have foundered except one, the Ruger Blackhawk .30 hunting revolver with 7 1/2″ barrel.
Simply put, a cartridge with those sort of ballistics and conventional propellants is going to (1) have high breech pressure by handgun standards and (2) need a fairly long barrel to even come close to a complete propellant load burn before the bullet exist the muzzle.
Practically speaking, you’re not going to accommodate those two factors in a service-sized automatic pistol. It’s a big enough PITA doing it in a hunting-sized revolver.
And in return for blown primers and stupendous muzzle signature, you’re basically going to get at best ballistics in the range of some of the more emphatic hunting revolver loads in .357, .41 and .44 Magnum. That have been around for longer than most of us have been alive.
With the exception of the standard “full-load” .357s and “medium-velocity” .41s and .44s, those round are generally considered too much of a good thing for law enforcement due to training problems. In the military, even more so.
7.5x27mm sounds to me like another “boutique” cartridge likely to appeal to special operations units and private owners wanting a pistol which can penetrate body armor. And I can easily imagine the “authorities” reaction to the latter; the 5.7x28mm FN all over again.
What would be interesting would be seeing it in a sporting rifle. we haven’t really had a good small-to-medium bore small game/pest control round in a reloadable (i.e., centerfire) rifle cartridge since the demise of the .218 Bee,.32-20 WCF, and .256 Winchester lo these many years ago.
In a lightweight bolt-action or even lever-action carbine with a box magazine, this round would fill an actual need long ignored by the gunmakers and ammunition manufacturers.
clear ether
eon
Should be “exits” of course, but WordPress keeps completing “than” as “that”, too.
grr.
clear ether
eon
@ kirk.
7.5 FK is not rocket science. It’s a shortened 6.8 SPC with 9% less pressure (50.000 PSI instead of 55.000 PSI. 50.000 PSI is also the pressure of the 5.7×28 FN, so not unheard of for a pistol). If the cases have problems, it’s a manufacturing problem.
It’s an interesting cartride because, power-wise is an intermediate cartridge fired from a pistol. Out of a carbine barrel, it would have roughly .222 Remington muzzle energy.
Dogwalker,
Yes, exactly, and .357SIG (and .30USC) are 40K (a whole 3.8% over 9+P!).
Bart, I respectfully disagree. A selfloader is a straightpull bolt gun with gas or recoil working the “handle”. It can be challenging to get enough oomph out of .22LR or .25ACP to deal with dinged or dirty ammo, chambers, etc., but that diminishes as energy goes up.
It is, however fair to say that it’s tough (particularly with the limited free recoil travel of a pistol) to develop a semiauto action that can deal with a broad range of energy, like 10mm, without either balking at the low end, or beating itself up. .357SIG is easier because every load is full-power. 7.5 should be even easier to troubleshoot given its narrow range of bullet weights, if it doesn’t fade into obscurity.
@ eon
It has about the muzzle energy the .30 Carbine has out of the M1 Carbine (but far better ballistic coefficient), but from a pistol lenght barrel.
Same barrel lenght, the 7.5 FK is a fairly more powerful cartridge, and it can’t be different, since it has higher case volume (+0.1 cm3) and higher pressure (+10.000 psi).
As said, out of a carbine barrel, the 7.5 FK has roughly .222 Remington muzzle energy, that means just a tad short of .223 Rem or, looking at similar calibers, it’s not that distant to .300 Blackout. It’s really in intermediate cartridge territory.
@ Mike
Considered already the 5.7x28mm FN, with the same pressure, doesn’t want to be fired by a Browning tilting barrel system, I wonder if also the 7.5 FK would be better served by an action that provides a little cam action in extracting.
Dogwalker,
It would be interesting to see if they could make the FiveseveN’s “Glisenti” action work with the higher breechface area / bolt thrust, or better yet the MP57’s (which I have, and love).
“(…)What would be interesting would be seeing it in a sporting rifle. we haven’t really had a good small-to-medium bore small game/pest control round in a reloadable (i.e., centerfire) rifle cartridge since the demise of(…)32-20 WCF(…)these many years ago(…)need long ignored by(…)ammunition manufacturers.(…)”
Now I am extremely confused, after scrying https://www.midwayusa.com/32-20-wcf/br?cid=7535 there are 6 different offerings of 32-20 WCF, including Remington High Performance Rifle and Winchester Super X. Are these no longer produced and they only sell existing stock?
@ Mike
Since the Revelli rotating wedge worked from the original 7.65 Glisenti up to 8mm Breda, I have little doubt it can be adapted to 7.5 FK.
However it would be even simpler to turn the Browning action of the FK Brno into a rotating barrel action.
Dogwalker,
Agreed – I understand that everything is scalable. OTOH, I’ve found that some design ideas (including some of my favorites) aren’t always scalable into light, handy, snag-free pistols.
With the rotating-barrel action, a side benefit is that the can goes on the barrel jacket, eliminating the need for a Nielsen device.
Yeah. While everything is scalable, much rifle caliber actions are too complex to be really compressed into a pistol (other than the Revelli action, something had been done with roller delayed and roller locked, and obviously the Frommer Stop long recoil).
Sounds like the desire for a super powerful round got ahead of good design. Looking at other reviews, there is a lack of consistent quality across the various manufactures of the ammo. And when you add in the high cost of the ammo, I don’t think this round will gain major acceptance.
As I point out above… I think it’s more that you can’t make these things work reliably with modern materials technology. Anything soft enough to work with a conventional firing pin ain’t ever going to be strong enough to withstand the pressures generated here. Not consistently enough for affordable mass-production, anyway.
The path forward for these high-pressure cartridges is either going to have to be a totally different priming method for the cartridge; something that doesn’t rely on a ductile copper primer sealing the cartridge and then withstanding all that pressure.
“(…)ductile(…)”
If you do not want to have primer of this type then use VOERE https://www.thefirearmblog.com/blog/2016/12/08/laser-ignition-system-voere-x3-rifle/
The 327 federal is a modern improved 32-20 and is available in Henry’s. I have a custom 616 revolver and it is a great round
.327 Federal is an improved and lengthened .32 H&R Magnum. It stands to that as .357 Maximum does to .357 Magnum. .327 Federal has nothing in common with .32 WCF (a bottlenecked round as opposed to a straight wall) other than bore diameter.
.32-20 is an over century-old, bottlenecked, rimmed cartridge designed originally to work in lever-action tubular-magazine rifles, and to a lesser extent revolvers. Today it is mainly a boutique round for cowboy action shooting and other nostalgia buff activities.
It has badly needed to be replaced by a modern successor cartridge, capable of being accommodated in something other than a tube magazine repeater or a revolver, for most of a century. That means rimless, preferably straight-walled for a revolver, and bottlenecked restricted to bolt-action, pump or self-loading actions with box magazines.
The 7.5 FK would seem to be nearly ideal as a “light” rifle cartridge. In a handgun, it’s questionable for the reasons already stated.
clear ether
eon
Yes to a rifle, though not a semi-auto. This would take down the majority of game animals, in a lighter package.
There still is the issue of manufacturing quality of the ammo. Nothing will fix that until the round becomes non-proprietary and cheaper. But maybe the ammo quality issue is all about trying to jam too much power into a semi-auto pistol.
As I’ve said, it would be a great PDW/Sub round. Just FK has not managed it.
Regarding 327 Federal. never said it was the same, just a 32-20 modern. Obviously not for autos. That would be the 30 Super, which while I’d like to see it be mainstream, it likely won’t.
Bottleneck handgun rounds are popular with some of us. I still reload 9×25. I built a 9×30 as an alternative to the 7.5 but very little interest. It does bypass the patents.
Christian Haller,
Was your 9×30 also 10mm Mag based, or did it use a different parent cartridge? I like the idea of more 5.56-based cartridges in this performance envelope.
Mike – I basically copied the 9×25 on the 9×30 case, worked up the load. Used a 10mm mag case from Star
Christian Haller,
Thanks!
I’m over 1000 rounds with mine with no failures at all. It’s an early version. It sounds like the ammo or gun have changed. Would to see this round in an APC. Unfortunately it’s been completely mismanaged by FK
B&T Straight Blowback system could revolutionize this round. FK won’t release the round for commercial productions, crippling it. APC 7.5 would be amazing
I don’t think so. Considered the relatively high pressure and diameter of the bullet and case, this round would require over 1kg bolt mass to be fired from a pure blowback system.
It has a buffer and also works with 308. So I’m sure they would make it work well
Also the Volkssturmgewehr 1-5 had a buffer (the gasses), but it still required a 1.4kg mass bolt to work. The buffer reduces the peak force of impact of the bolt in the frame, it doesn’t delay action opening. it’s only the mass that does it.
Having the same pressure, but smaller base surface, the 7.5FK would require at least a 1.1 kg mass bolt. To reduce that, you need a delayed blowback system. With a roller delayed blowback system, a 100g bolt and 300g carrier would probably be enough.
The B&T 308 uses a standard piston system.
Thanks for the engineering lesson. Our simulations just say otherwise. I’ll turn in my degrees. No longer interested.
Kirk — If we are talking about detonating high-pressure rounds, then let’s talk about the really high pressure rounds in modern artillery pieces. How is the propellant charge in these ignited? Would such a system scale down to pistol/rifle size?
I agree with you that trying for a super, one-shot-kill any living creature on the planet round for a handgun is silly. Shot placement is more important than power. Remember the story of a woman how killed a grizzly with a .22. Handguns are innately less accurate than long arms. The situation is not helped with a pistol that has an overly powerful cartridge with increased recoil and muzzle flip.
@Bart,
In artillery, obturation is usually achieved by something like replaceable copper O-rings that the breach seals on, in systems without cases that use bagged charges. The cased ones are generally primed, but with primers that are either electric or of a far different type than the flimsy copper shells used in small arms. The assemblies for the percussion system are flippin’ huge, by comparison.
I don’t think artillery has a small-arms relatable solution. Not anything that’s easily and affordably mass-produced, at the moment.