Anybody playing with the 7.62x25?

[benewton]

Having just purchased a CZ-52, since you've got to use the C&R once you've got one, I now get to play with the 7.62x25 Tok.

From the limited load data I've got, it looks like the beast can come within 100 fps or so of .30 M1 carbine ballistics with AA9 and a 110.

Either something's wrong here, or this is a REALLY good round.

Anybody else reloading it?

 

[cls12vg30]

You might want to check out "The Czech Weapons Board" at gunboards.com, there's several people there who reload Tok. And no, nothing's wrong. It IS a great round.

 

[NavajoNPaleFace]

The round is basically a shorter version of a .30 caliber rifle round.

It's very impressive and I'm surprised the American gun and ammo unions haven't come out with their version of bottle necked beast over the years.

 

[Black Snowman]

From what I've read here and on other reloading forums the most popular and accurate bullet for the gun is the 100 grain Hornady XTP. I have everything I need but haven't actually gotten around to loading any yet

If you get poor accuracy a lot of people recommend you slug the barrel as the CZ-52 can vary a bit in bore diamater depending on vintage and use. You may need to bump up to a .311 caliber bullet if you have one of the "loose" bores.

Maybe I'll reload some 7.62x25 tonight . . .

 

[benewton]

Thanks, all!

I was unaware of gunboards...

More the silly me.

I'm not all that impressed with the -52, although I've the urge to spend more bucks on grips, firing pins, and sights, than the weapon's initial cost, but that round is very interesting, to say the least.

Carbine energy levels, not to mention armor penetration, in a two pound weapon, and that's before the "reloading" touch... I've at least got to look.

Again, thanks all, as I depart down the trail of improving an unnecesary tool.

Still, it'll give me an excuse to get the chronograph, not to mention the digital micrometer, so all's well that ends that way.

 

[Clark]

Don't play around with the AA#9 loads published by AA between 2000 and mid 2004.

The late 2004 data from AA is dumbed down to the 30 Mauser loads [level of pressure] that Hornady and Sierra publish.

The problem is the CZ52 is not very strong. The bottom of the chamber is thin. The slot for the rollers in the bottom of the barrel cuts into the chamber strength.
It may be the cheapest pistol for sale in America right now, but it is not the best designed.

 

[benewton]

Caution with reloading data is ALWAYS a good idea.

That said, the loading "data" which came with the new Lee dies shows starting load of 10.5 AA9 behind a 110 jacketed, with a max of 11.7 for a claimed velocity of 1688 fps.

Now, they don't give the primer, bullet maker and diameter, weapon, or barrel length, so I'm not sure that the data means anything at all. Investigations of my manuals show loads far below that for the "standard", read light, bullets.

Now, in my normal reload ops, I don't even try for the highest velocity, figuring 50 fps or so is meaningless, and, besides, using a Dillon, I'd prefer the safety margin of a bit less propellant.

But this isn't a "useful" weapon, and I'm thinking, for the first time in better than 20 years of reloading, of really exploring what this round can accomplish. At first pass, it sure looks like a good starting point to me, being
reasonably close to the M1 carbine in a hand weapon.

Not sure about the -52's strength: the lockup looks secure enough to me, and I don't see any way to use an Oehler PBL for pressure monitoring. So, I guess it'll be case web expansion, and the old fashioned machine tool measurement devices.

Since I can, and do, shoot just outside our rear sliding door, I'll get the chance to load 5 at a time, check cases as I work up, and, it'll give me an excuse to buy the chronograph!

One thing that I am sure of: this isn't a .30 Mauser, so pressures for that round are irrelevant. More or less the 45-70 thing as far as US manufacturers go, but I'm loading for a specific weapon.

Again, thanks for the help, all. It'll be a few months, if I get to the project at all, but I'll pass on what I find out.

 

[Clark]

The 30 Mauser and the 7.62x25mm Tokarev are the same [or so close to the same dimentionally, that the difference is lost in the tolerances] except for the pressures.

Tokarev ammo from Russia is at 30 Mauser pressures, but Tokarev ammo from Poland, Bulgaria, Rumainia, China, Austria, and the Czecks is 42kcup.

The problem is the bottom of the chamber in the CZ52 fails long before the roller locking system does. It is ~ .045" thick. This was the thinnest chamber I have measured until Kel-Tec came out the the P3AT .380. But the Kel-Tec is heat treated to RC42, 4140.

What ever they made CZ52 barrels out of, it should not have been so thin on the bottom, and it splits and crumbles.

What does it all mean?
Don't use the 1680 fps 110 gr data from Ted Curtis in 2000.
Don't shoot surplus Tokarev ammo in a CZ52.
Don't shoot new imported 7.2x25mm ammo in a CZ52.
Load books say the CZ52 is strong. Call them and ask them where they got that information. I have. They say they read it somewhere. They are wrong. Let's hope for some real corrections on the subject in the next generation of load books.

 

[Gewehr98]

A caveat is very much in order here.

Ask Clark what load did blow that CZ-52 barrel he pictured above.

I'll give you a hint, it's higher than published reloading data.

I've used Ted Curtis' load data for my own CZ-52 with no problems, and that's using S&B/Starline brass, Sierra and Hornady XTP bullets. Well before I got to the level of blue-pill loads like Clark runs, I ran into pressure signs with the primers, etc. That was my clue to stop.

Not everybody loads guns with homemade proof rounds to find the barrel's failure point. Some of us don't consider our handguns to be disposable.

I'll leave destructive pressure tests to unbiased folks like H.P. White Laboratories. They do it for a living.

 

[Clark]

1) I don't think White labs would have tested a CZ52.

2) But I would not know if they have, as they tell me that test results are confidential with the client that supplies the gun and the fee.

3) I suspect [based on my experiments] the CZ52 would have failed a conventional proof test per the SAAMI ratio of 1.3 to 1.4 times the working pressure for centerfire pistols of 21,100 psi or greater, as 1.3 to 1.4 times 42 kcup [49,000 psi] is 63,700 to 68, 600 psi.

While my tests are not conclusive, as far as I can find out, there is nothing else available, except the load book tribal lore which can be shown to be in error.

--
Be careful what you pray for, it can happen.

 

[gandog56]

I have not heard of any kaboom stories from people shooting milsurp in a CZ. But I have sure seen you in other forums putting down CZ's. Usually just before the moderators lock them.

 

[Clark]

Gandog56,

You used the search function to go back 4 years to defend your CZ52's virtues.

Since then someone was hurt at my range in Issaquah, while shooting a CZ52 with surplus ammo.

Since then a collaborator and I tested a quantity of CZ52 barrels at the prestigious Jet Propulsion Laboratory for hardness [in all fairness, and ordinary Rockwell harness tester] and the metal of the barrels is terrible. The data varies between RC25 and RC35.
That might be ok for Grandpa's Damascus barrel 12 ga for black powder, but it is not ok for 42,000 c.u.p. when the chamber is .056" thick.


And I don't see any moderators locking down threads at THR reloading becuase posted data and calculations contradict published materials. Those forums that do so are running short on posts from me.

 

[destrux]

From what I have seen, the most commonly used (and supplied) load data for this round results in velocities in the 1100-1300 FPS range with 80-90gr bullets backed by either Unique, Bullseye, or AA-5. Most people reload to save money or gain accuracy, so most who would reload this round are doing so fairly safely.

It's only those who are asking for trouble who seem to be finding it with the CZ-52. I have only heard of people blowing barrels with one batch of known defective surplus ammo (which most shooters of 7.62x25 now know about).

I routinely shoot S&B white/green/red box ammo (known to be hot, in the 1550FPS range), along with romanian surplus (also known to be in the 1450 FPS range). and with over 3000 rounds through my 1954 non-rearsenaled CZ-52... I have never blown a barrel, broken a firing pin, and have no cracks in my chamber or barrel. If this gun is so terrible and weak, someone forgot to tell mine.

 

[NCsmitty]

I had a CZ-52 for a while and reloaded for it. I shot Speer 100gr. Plinkers backed by 7.5 gr. of Unique. It shot well with this load and was more mild than S&B factory. Nice gun for the money but just didn't feel right in my hand so I sold it.

NCsmitty

 

[mkl]

If this gun is so terrible and weak, someone forgot to tell mine.

Mine too.

I've got three of them, one with over 1500 rounds of Bulgarian and Polish surplus ammo through it. The rounds chronograph at 1440 to 1480 fps with an 85 grain FMJ bullet.

Never reloaded for it since the surplus ammo was so cheap. Only watch out I heard was not to dry fire the gun because of the cast firing pin.

Not to say the above cautions are not in order, since I have never tried reloading; just that the "factory" surplus ammo has never given me a problem in any of my three CZ-52's.

 

[GaryL]

Since then someone was hurt at my range in Issaquah, while shooting a CZ52 with surplus ammo.

There is some surplus 7.62x25 that is known to be hot and variable (i.e. some rounds in a tin may be unsafe). I think it was Bulgarian, (it would either have been Bulgarian, Romanian, or Yugoslav), but don't quote me on that. It was for a specific range of years, and published a while back. I read about it once in a periodical, and never saw it again.

I suspect some wholesalers may have quietly unloaded it as MG ammo or something like that.

 

[jr45]

I reload the 7.62x25 for my CZ-52. Typically, I use 10 grains of AA#7 under a Hornady 85gr HP bullet. Overall, very good results with no signs of over-pressure. The main problem I have is the CZ-52 throws the brass pretty far and it becomes a real pain trying to police them up. I also use the Bulgarian and Yugo surplus ammo. The Yugo seems to have a very hard primer and sometimes needs a second strike to set them off and the Bulgarian has a bit louder report (still no signs of over-pressure).

 

[mkl]

There is some surplus 7.62x25 that is known to be hot and variable

I may be able to help here. I downloaded this page in 2002. Link does not work anymore. I made copies of this and pasted it to the top of my "tuna cans" of 7.62x25 ammo.

Scan attached. Blow it up to full screen size and you should be able to read it.

 

[CBS220]

Holy thread necromancy, batman!

 

[Clark]

Holy thread necromancy, batman!

In 2005, John Bercovitz* and I bought 10 CZ52 barrels and tested them for hardness at JPL, where John Worked. Measurements between RC25 and RC35 were taken on intact 7.62x25mm barrels. A more modern 9mm CZ52 barrel tests at RC47.
My 9mm CZ52 barrel steel might yield at 220ksi, while my 7.62x25mm Tokarev CZ52 barrel steel might yield at 120 ksi.

What does this mean to the non engineer?
The CZ52 is the only semi auto pistol I have ever tested that is weaker than the brass.
It does have the thinnest chamber, except for the Kel-Tec P3AT

Why does the CZ52 blow up in a work up, and no other pistol will, even the P3AT?
The P3AT is made of very strong steel.
The CZ52 is made sometimes mediocre steel, sometimes terrible steel.
The CZ52 cartridge has a larger diameter, causing more hoop stress for the same pressure.
The P3AT has poor case support, allowing only low pressure in a work up.
The CZ52 has good case support good enough to allow the primer pocket to be the limit of the brass, if the barrel did not split first.

* John Bercovitz who figured out how to calculate 357 mag brass stretch in 1993

 

[jr45]

Clark,
I guess I'm a little confused. If the barrel of the CZ-52 is weaker than the brass, then I would assume that the barrels would be spliting at a very alarmig rate (i.e. everyone would know they were bad/like firing smokeless powder out of an black powder gun). I am not an engineer and yet I have fired close to 2k rounds of varous surplus ammo through my CZ-52 (and about 500+ reloads) with not ill effects. Does this mean I'm just lucky? If you could explain why there are not so many accounts of the barrels spliting?

Note: I am not tring to question the testing you conducted...just basing my personal experiences in the question.

 

[Halo]

The main problem I have is the CZ-52 throws the brass pretty far and it becomes a real pain trying to police them up.

Absolutely! I've been trying to build up a brass collection for eventual reloading, but I'm beginning to wonder if it'll be too much trouble. I've actually found a bunch of my 7.62x25 brass up in tree branches.

 

[GaryL]

mkl - thanks for the data.

 

[Funderb]

oh here it all is again.

I can't wait for my cz to blow up in my face. Looking at clark's data, it's a matter of time only.

Some people go out of their way to make as much bad press for things as possible, ignoring that they are a very small sample indeed.

Next thing you know CZ52s will be right net to jennings/bryco line SNS's

 

[AgentAdam]

SportsmansGuide has 9mm conversion and factory barrels for the cz-52.