7.62x25 K Frame

[keithhagan]

Has anyone tried or considered how to make 7.62x25 work in a revolver? It has the same case head as 9x19, so moon clips should be plentiful, and out of a longer barreled revolver should perform quite well. I tried a full 9mm moon clip of 7.62x25 in a 940 for fit and they looked just fine. Although necked cartridges have some trouble in revolvers compared to straight-walled cartridges, the moon clips might prevent interference with the action caused by neck expansion (or bend, who knows).

I'm having a K-frame built for .327 Federal Magnum and thinking about having a second cylinder chambered and cut for moon clips for 7.62x25 fitted as well, as an alternative to 32-20.

The CIP standard for 7.62x25 here shows a 7.9mm, or ~.311", bullet, which should work out just fine since the SAAMI specs here for .327 call for a .312" or 7.92mm groove just as the CIP specs do for 7.62x25. One note, the CIP specs call for tighter (7.62mm vs 7.70mm) but fewer (4 vs 5) lands than the SAAMI specs.

Although I know a lot of factory loaded ammunition comes with a .309" bullet, I imagine the performance/safety shouldn't be any worse than folks who have had the cylinders on their .357 chambered revolvers cut for 9x19 (.355 vs .357 bullet). In any event, I hand load 7.62x25 with .312 bullets.

 

[CH4]

Never heard of it, but sounds like an interesting project.

 

[Protocall_Design]

It wouldn't take that much to rechamber and fit a new cylinder to an existing gun. I think it would be worth a try. If you do it, let us know how it works out.

 

[Engineer1911]

Talk to a Model 53 / 22 Jet owner to see how bottle neck cartridges work in a revolver.

 

[WR Moore]

The problem with bottleneck cartridges in revolvers is case set back due to the sloping case shoulder/case taper. Moon clips won't do a darn thing to mitigate that issue. You might also read up on the .357 Bain & Davis, this was (IIRC) a .44 magnum case necked down to .357. While interesting, it proved troublesome and didn't set the world afire. I believe it used a sharper shoulder angle than the .22 Jet. No idea what the shoulder angle of the 7.62 x 25 mm / 7.65 Mauser is.

 

[austintexas]

K hornet has a shoulder and seems to do just fine.
SWCA 892

 

[Kurusu]

That concept

Seems to be a solution for a non existing problem.

 

[old tanker]

Performance? Kinda like a rimless .32-20, ain't it?

 

[cwneely]

I have tried it (in an Italian SAA). It doesn't work. Case is jammed against recoil shield and shoulder does not allow it to move forward. It might work if you were to make a reamer with a straight taper but I never went that far.

 

[keithhagan]

I have tried it (in an Italian SAA). It doesn't work. Case is jammed against recoil shield and shoulder does not allow it to move forward. It might work if you were to make a reamer with a straight taper but I never went that far.

Thanks, cwneely. This is the issue I think will be the problem. In a double action, as opposed to a single action, my hope (without running the math on the physics) was that the availability of moon clips would increase the mass moving toward the recoil shield from a single spent case to a system composed of one spent case and (up to) 5 loaded rounds and the increased friction to go along with it so that the case heads would not interfere with the action. Having experienced the jamming first hand, what does your gut tell you about that idea?

The idea of reaming a tapered chamber instead of a necked one is interesting, but I wonder if the fact that the cartridge headspaces on the shoulder would make that a non-starter.

 

[bulletslap]

Around 20 or 25 years ago some outfits offered to rechamber 7.62 Nagants to 7.62x25 Tok. I don’t know if they had problems with cases sticking or had cylinder lockup; as they had quite a few KaBooms and that minor fad quickly ended.

 

[Green Frog]

Thanks, cwneely. This is the issue I think will be the problem. In a double action, as opposed to a single action, my hope (without running the math on the physics) was that the availability of moon clips would increase the mass moving toward the recoil shield from a single spent case to a system composed of one spent case and (up to) 5 loaded rounds and the increased friction to go along with it so that the case heads would not interfere with the action. Having experienced the jamming first hand, what does your gut tell you about that idea?

The idea of reaming a tapered chamber instead of a necked one is interesting, but I wonder if the fact that the cartridge headspaces on the shoulder would make that a non-starter.

Since you are going to be using moon clips, wouldn’t they effectively become the basis for headspace?

To me, it looks like you are trying to go all around the barn to end up with a gun that will do about what a 327 Fed Mag does... and you’ll have extra work to do it.

I’m as much in favor of experimental gun building as the next guy, but I like to see some predictable advantage to be gained from the work... this strikes me as “pure science,” just doing an experiment to see “what if?” I’ve got enough projects on my plate already, but if this strikes your fancy, I definitely think you should go for it!

Froggie

 

[DWalt]

I like such projects, but I probably wouldn't undertake this one for the reasons stated. High pressure bottlenecked cartridges are not ideal for use in a revolver. I'd think a cylinder chambered for the .327 (or .32-20 with hot handloads) would produce about the same ballistic performance as the 7.62x25 with a .32 bullet, so there is not much of a practical reason to do it. Maybe .30 Carbine? At least Ruger made a Blackhawk in .30 Carbine, and it works (I have one of those but usually download the cartridge to a .32-20 level using lead bullets, as the muzzle blast and noise from a FMJ GI load in a revolver is formidable).

 

[keithhagan]

Since you are going to be using moon clips, wouldn’t they effectively become the basis for headspace?

To me, it looks like you are trying to go all around the barn to end up with a gun that will do about what a 327 Fed Mag does... and you’ll have extra work to do it.

I’m as much in favor of experimental gun building as the next guy, but I like to see some predictable advantage to be gained from the work... this strikes me as “pure science,” just doing an experiment to see “what if?” I’ve got enough projects on my plate already, but if this strikes your fancy, I definitely think you should go for it!

Froggie

Thanks for your response, Frog.

To your first comment, with the moon clips, you're right, but with a tapered chamber, that might have the negative consequence of eliminating the possibility of shooting without the moonclips. In fairness, that would essentially never happen, as moonclips are one of the pro's of the cartridge.

To your second, I don't mean to pick on you, but if we start walking down the path of "should" it be done, that's a slippery slope. A very large portion of this forum would be pointless if we allowed ourselves to head in that direction.


From everyone's input, it seems that, fundamentally, this can be done, but to make it practical, the problem remaining that we must address is case head-recoil shield interference when the neck expands and pushes against the chamber wall after ignition.

Proposed solutions are:

• Build on the 547 frame to take advantage of second pin securing cartridge (expensive, no stainless option, fixed sights)
• Tapered, instead of necked, chambers to reduce bearing surface and angle of force vector (reduced reload life of brass?)
• use moonclips to combine mass/friction of six rounds to retard rearward travel (moonclips may not be robust enough and may bend instead, incremental rearward travel after each shot may result in jamming anyway [shouldn't hammer reset position after each?])

Anymore ideas for solutions or empirical/analytical critiques of these not already addressed?

 

[Hondo44]

Talk to a Model 53 / 22 Jet owner to see how bottle neck cartridges work in a revolver.

22 Remington Jet (22 Centerfire Magnum)

It wasn't the bottle neck, it was the long sharp tapered bottle neck that caused extraction problems with this cartridge. Wildcatters resolved this problem by changing the case to a sharp shoulder similar to the 256 Winchester Magnum, another cartridge based on a necked down 357 case.

The Jet improvement wildcats are known as the 22 Super Jet, Improved Jet and the Saber Cat.

 

[DWalt]

I have to wonder why S&W was seemingly unaware of the problems associated with a revolver chambered in .22 Jet before it went on the market. Didn't they prototype the idea first? And then there is the Boeing 737 Max anti-stall device.

 

[Hondo44]

I have to wonder why S&W was seemingly unaware of the problems associated with a revolver chambered in .22 Jet before it went on the market. Didn't they prototype the idea first? And then there is the Boeing 737 Max anti-stall device.

S&W likely figured their warnings to keep the chambers squeaky clean and free of oil were sufficient.

Your Boeing 737 Max example (and other aircraft pre-testing calamities I can thing of) is truly an apropos analogy, albeit with much more dire results!!

 

[Rule3]

Thanks for your response, Frog.

To your first comment, with the moon clips, you're right, but with a tapered chamber, that might have the negative consequence of eliminating the possibility of shooting without the moonclips. In fairness, that would essentially never happen, as moonclips are one of the pro's of the cartridge.

To your second, I don't mean to pick on you, but if we start walking down the path of "should" it be done, that's a slippery slope. A very large portion of this forum would be pointless if we allowed ourselves to head in that direction.


From everyone's input, it seems that, fundamentally, this can be done, but to make it practical, the problem remaining that we must address is case head-recoil shield interference when the neck expands and pushes against the chamber wall after ignition.

Proposed solutions are:

• Build on the 547 frame to take advantage of second pin securing cartridge (expensive, no stainless option, fixed sights)
• Tapered, instead of necked, chambers to reduce bearing surface and angle of force vector (reduced reload life of brass?)
• use moonclips to combine mass/friction of six rounds to retard rearward travel (moonclips may not be robust enough and may bend instead, incremental rearward travel after each shot may result in jamming anyway [shouldn't hammer reset position after each?])

Anymore ideas for solutions or empirical/analytical critiques of these not already addressed?

Proposed "solution's" But for what end? Other than just a project?


As mentioned the 327 Federal cambering will probably do as well or better. If you don't reload, neither ammo is cheap. The only cheap 7.62 is corrosive ammo.

Shoot a light bullet in a 327 Fed Mag and you have a zippy round!

 

[Sevens]

I absolutely love projects and I've always been/always will be in favor of folks doing anything they wish to do with their own guns regardless of what other folks think when it comes to *GASP* "altering something original."

With that said:

Build on the 547 frame to take advantage of second pin securing cartridge (expensive, no stainless option, fixed sights)

This is going to be a losing proposition/money pit if the plan includes taking a 547 and altering it, simply because of the (ridiculous) market for the 547.

Sure, if you found a blown or otherwise wrecked/modified 547, but altering a fully functional one would be akin to taking a classic original muscle car in high condition and making a dune buggy out of it. You could do it, but it would be like igniting stacks of currency.

Could you take a random K-38 and attempt to replicate the frame feature of the 547 securing pin?

 

[Hondo44]

Anymore ideas for solutions or empirical/analytical critiques of these not already addressed?

I think you've tapped out this group for any more information. Your next step is to contact custom revolver smiths and get their opinions. They'll support it or possibly bring up things not yet thought of. Either way you've pursued all avenues of consideration. Then the only thing left to do is follow your passion and go for it, then you'll know for sure if it works or not.

I wish you success!