7.5 FK Field Pistol; interesting concept

[Onty]

No. See when one says, "Accuracy is touted as a 1.5 inches at 100 meters." I take that with some, uh, amusement.

Deaf

Looks to me from video that this is the accuracy from test barrel.

From what I understood, the goal was accuracy from pistol 100x100mm (4x4 inch) on 100 meters.

According to old books from Europe, same accuracy (100x100mm on 100 meters) for hunting rifles was considered as a very good one. Well, technology is better now.

 

[Onty]

Going through these websites about new 7.5 FK cartridge, I found following statements:

The 7,5 FK is a completely new proprietary cartridge caliber. The case is 27 mm long, the total length of the cartridge is 35 mm, and the head diameter of the case is 10,8 mm. This caliber is not a necked down version of any other caliber. The case is designed to withstand higher pressures than is usually used in pistol calibers.

http://www.fkbrno.com/en/7-5-fk-system#the-cartridge-8

The new FK Brno cartridge is officially called the 7.5 FK. It is a bottleneck design that is not based on any existing cartridge cases, so don’t expect to make your own with existing brass.

http://www.gunsholstersandgear.com/2016/07/19/worlds-fastest-handgun-not-7-5-fk-brno/

I cannot comment about case strength, but if the pressure is close to standard magnum pistol and revolver cartridges (36 000 PSI), we might have case that could be used to make 7.5 FK brass; it's 10mm Magnum, and Starline still has it on stock. Well, it is longer than 7.5 FK brass, but any skilled reloader can trim it in no time.



7.5 FK round



10mm Magnum round. Be ware that .425" is 10.795mm, basically 10.8mm

So, if you want to get 7.5 FK pistol and reload, I would suggest check first what is max. pressure in 7.5 FK, and can 10mm magnum brass take it. If so, go to Starline https://www.starlinebrass.com/brass-cases/index.cfm?cid=2 and by 10mm Magnum brass while is available. Funny thing is that according to http://www.starlinebrass.com/ , this brass is second best selling one. Looks like that some folks started already stockpiling it. I would say to make 7.5 FK, because last pistol in 10mm Magnum handgun was made decades ago, and only one I know about was AMT.

 

[Deaf Smith]

Looks to me from video that this is the accuracy from test barrel.

From what I understood, the goal was accuracy from pistol 100x100mm (4x4 inch) on 100 meters.

According to old books from Europe, same accuracy (100x100mm on 100 meters) for hunting rifles was considered as a very good one. Well, technology is better now.

Well IF the gun can actually shoot that tight a group... question becomes can YOU shoot that kind of group.

Something tells me it ain't gonna work out as they think it will.

Deaf

 

[RX-79G]

Nice looking gun. I like the idea.

It's surprising how light it is at 45 oz. An all steel P226 weighs over 42 and isn't nearly as large or have as much going on.

 

[Onty]

Well IF the gun can actually shoot that tight a group... question becomes can YOU shoot that kind of group.

Something tells me it ain't gonna work out as they think it will.

Deaf

Top notch accuracy is always welcome. IMHO, nothing helps to build confidence and shooting skill as accurate handgun, and nothing kills them as handgun that makes shotgun pattern on the target.

The worst thing new pistolero could do is to get first handgun that is not accurate. I know this first hand. That is the reason I always suggest to beginner as a first handgun TC Contender in 22LR; accurate as rifle, with trigger that could be tuned as on bullseye revolver. Once confident in his shooting, new shooter could move on something else, and always get his money back selling Contender. Wish I had that advise when started shooting.

 

[Onty]

Just found this statement regarding possible price for 7.5 FK pistol:

And on top of all that, there’s the matter of what such a gun will cost, and rumor has it that could be well north of $5,000.

http://dailycaller.com/2016/05/03/the-worlds-fastest-pistol-7-5-fk-brno/#ixzz4I6KpAhop

Seems to me way too much. I doubt that it will go so high. 2500 bucks seem looks more likely, and even that is quite high for production gun.

Well, I have to admit that folks from FK Brno are smart. OAL of the round is 35mm (1.378"), whole 2.5mm (.100") longer than max. OAL that could fit into 1911 platform.

If this round takes off, I would say it's just a mater of time we see elongated version of 1911 that will accept 7.5 FK round. And if so, boy, that will open whole new world regarding new powerful cartridges in semiauto handgun.

 

[Wreck-n-Crew]

Thought we had a thread on the 7.5 FK Brno last year? I know i remember a discussion on it...maybe it was somewhere else?

Anyhow there's been enough wildcat and new cartridges over the years and some compare energy wise and many have came and gone. Like the 460 Rowland fe. It still exists and most that have one reload for it last i checked.

The upside to the 460 is conversions are easy enough and somewhat affordable.

Downside is it will beat a gun up quicker and if you don't reload then you only have a few choices for ammo manufacturers.

Cool factor seems more like the in factor as far as most new cartridge go. Over time they often fade.

Proprietary is another hitch in the negative category. At least for me.

With 10mm making a heavy comeback and .357sig hanging around i doubt it will last too long. But who knows? I've been wrong before!

I think the 2 things that kept the 10mm going was the fact that its easy and affordable to reload. That and Glock keeping a good supply of affordable 10mm pistols in stock. Plenty of power and a lot of fun if you ask me.







Sent from my LGLS991 using Tapatalk

 

[barnbwt]

This one's small bore, though, so the recoil will be less for a given p
operating pressure than a 45 caliber. They have a recoil damping system in the FK, but I notice there is no muzzle brake or porting, which leads me to believe the gun can handle the impulse just fine, and that the human is the limiting factor if any.

TCB

 

[Turkina]

Reminds me of 9mm Magnum. A dead round with only a hand full of known pistols that were made to shoot it. The AMT Automag III shot it in one variant, with the other being .30 Carbine.

I wish more gun makers would make pistols for the 9x23 Winchester. .357 Magnum performance in an autoloader...

 

[Kendal Black]

Just found this statement regarding possible price for 7.5 FK pistol:

[...]
Well, I have to admit that folks from FK Brno are smart. OAL of the round is 35mm (1.378"), whole 2.5mm (.100") longer than max. OAL that could fit into 1911 platform.

[...]

Heh! I hadn't noticed that. Good catch there--good observation, I mean. It will take time and plenty of money for competing firms to bring out competing products if the cartridge catches on. That also means, though, that the cartridge is less likely to catch on unless the one gun that shoots it (at the moment) turns into a smash hit.

I'm still wondering about light carbine and SMG/PDW companion pieces using the same cartridge as the wonderpistol. I have heard no peep about that. Perhaps the promoters do not want to dilute the idea of a new pistol by complicating the issue.

 

[RX-79G]

Hey, maybe they could rechamber the M1 Carbine to fire the round. Same performance, less mag capacity!




If the goal was to get a .30 100 grain bullet up to 2000 fps, that could be done with a wildcat of .45 or 10mm and have it fit in a standard magwell. With a Power Factor of 200, the 7.5 isn't asking more from the gun than stouter 10mm loads. Comparing it to .44 Magnum only happens because of the high velocity's effect on muzzle energy, not because this is a .44 Magnum comparable load.


So this doesn't appear to be an effort to get a new cartridge out there by being adaptable to other platforms, since it won't fit in a 10mm or .45 magwell. They are trying to create a freestanding caliber/platform system and sell it to rich people - I mean, gun enthusiasts.


The gun is very accurate, but it is about the same accuracy as several old service pistols - 4" at 100m is 1" at 25m, which a P210 or P9S will do. Les Baer sells a pistol that should do 3" at 100m.



So I wouldn't be surprised if someone could duplicate much of the 7.5 performance out of a 1911, USP, Glock, etc with the right custom barrel and some forming dies.

 

[barnbwt]

Hey, maybe they could rechamber the M1 Carbine to fire the round. Same performance, less mag capacity!

...from a pistol

I take it few have got ther mits (only partially) around the grip of a Kimball or Automag, yes? Suffice it to say they are nearly as stupid big as a Desert Eagle, only less powerful.

I think the 44mag comparison follows only because the FK is so freaking big. It's seriously either Robocop or Vash the Stampede scale.

If the goal was to get a .30 100 grain bullet up to 2000 fps, that could be done with a wildcat of .45 or 10mm and have it fit in a standard magwell.

Part of the appeal here is the long bullet which gives excellent range, reduced ballistic drop, and strong penetration characteristics (if only they used a tumbling bullet, enchanced wounding mechanics as well). Not really any good way to do a long bullet in a standard pistol magazine well without losing lots of powder/power, ending up with a 300 Blackout subsonic of a pistol cartridge.

TCB

 

[RX-79G]

BarnBT,

My M1 comment was about the suggestion to chamber a rifle in 7.5.




And my comments about .45 and 10mm Wildcats were about taking the 7.5 bullet and ballistics and duplicating them with cases and OAL lengths that fit in current platforms. If you did that you'd get exactly the same performance as 7.5 does without a special gun.

 

[Plastikosmd]

wow, a vash the stampede reference! sweet

 

[barnbwt]

RX, my point was that the combo of long ogive bullet and case taper would too much of the limited length in existing platforms, forcing the designer to skimp on powder volume --not enough room for sufficient mercy

TCB

 

[RX-79G]

BarnBT,

You lose 3mm in OAL, but with a .45 width case you would gain back the case volume you lost.

 

[Onty]

BarnBT,

My M1 comment was about the suggestion to chamber a rifle in 7.5.




And my comments about .45 and 10mm Wildcats were about taking the 7.5 bullet and ballistics and duplicating them with cases and OAL lengths that fit in current platforms. If you did that you'd get exactly the same performance as 7.5 does without a special gun.

Video about testing 40 Super from 6" barrel https://www.youtube.com/watch?v=DtvYcZiuaJM. Some loads are in 41 Magnum territory. Can you imagine what additional .100" of powder space will do in cartridge like this one?

 

[barnbwt]

You lose 3mm in OAL, but with a .45 width case you would gain back the case volume you lost.

My point is there's a fixed lower limit in length for what will allow us to reach a given power level, and I suspect a projectile of this length puts us above what will fit in a 45 --that's all. You've got the longer than usual bullet ogive that's exposed at like .5", then you have the neck that should have at least one caliber's length of .3" or so, then you have the rim/case head which takes up like .125", and you're left with less than 3/8" of volume that is itself taken up by the tail of the longer than usual bullet and shoulder taper.

By growing the case even by just the length of the shoulder taper or additional bullet ogive, you mitigate most of your powder-volume losses, especially if necking all the way down from 45 to 30 or 22. Not saying it can't be done, but obviously something's gotta give when you eat up all your volume for powder (and sadly, you can't just raise pressures & get proportionally higher results ). I think shortening this cartridge to fit a 45acp would result in performance reductions that make it indistinguishable from 357SIG at best, and not worth the effort. But since they let it grow enough to move into a distinct power band, it separates itself from such competition & has a better shot at success (assuming Automags are coming back into fashion )

I really want a movie villain contract-killer to have one of these

TCB

 

[RX-79G]

Barn,

I don't understand your objection. I did a rough calculation of the volume of the 7.5 case below the shoulder and compared it to the volume of a cylinder 3mm shorter but 1mm greater in diameter. The volume of that part of the case didn't change by much. The result would put the base of the bullet closer to the primer hole by 3mm, but the total volume for powder and air didn't change - it just moved from the area closest to the primer to the outer diameter of the .45 case.

So are you saying the geometry of the case at that point is somehow wrong, or are you saying the case volume would actually be smaller with a .45 case, despite the gain in diameter?


Pi x r² x length = volume of a cylinder

Pi x 5mm x 5mm x 17mm = 1335mm² 5.7
Pi X 5.5mm x 5.5mm x 14mm = 1330mm² .45 wildcat, 3mm shorter.

 

[Onty]

Seems to me that going with 7.5 FK Brno achieved two goals;

1. For the same pressure, with smaller case head dia reduced load on the face of the slide, and barrel could be smaller OD.

2. With longer OAL of the round made hard for manufacturers of standard 1911 to produce pistol that will shoot 7.5 FK cartridge. Considerable redesign will be required, and new tooling for magazines. From what I've heard, noted tooling is aprox. $250 000 investment.

 

[barnbwt]

I doubt tooling is all that great, seeing as it's CNC we're talking about; cost is probaly just ramping up yet another production line.

RX, my point is that a case is not a perfect cylinder, and that the longer neck required for a fatter case will eat some more length, and you still have the lost case length to deal with. How realistic is it this reduction would not drop ultimate volume and harm performance? 224 Boz also comes to mind, I thought its sharp shoulder had feeding, production, and case life issues?

TCB

 

[RX-79G]

You are right that the longer shoulder is going to eat some capacity. That loss is:

(2x5.5xPi - 2x5xPi) x .5 x .5 = .766
Subtract that from the previous calculated volume leaves you with 1329mm². It is just a tiny triangular section you lose by extending the .45 shoulder out to 11mm from 10mm.


I just don't think the extra 3mm of OAL length on the 7.5 bought them very much extra case volume over a slightly shorter, wider case. In other words, 7.5 isn't a very radical cartridge design and its ballistics could be achieved with other shapes without requiring unusual shoulder dimensions.

It would not be a radically expensive project to attempt to duplicate the ballistic performance with a .45 USP, custom barrel and forming dies.