A 1911 idea. Will I be banned for this?


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BCRider
August 17, 2012, 02:29 PM
So... I got an idea which may get the 1911 faithful sputtering up their lunch..... :D

A classic US 1911 chambered in the classic Russian 7.62x25. West meets East.

Whatcha all think?

The only fly in the ointment I can think of is that the rounds might be too long to fit in a magazine which still fits in the magwell.

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1911Tuner
August 17, 2012, 02:32 PM
I think you'd have a real problem getting it to cycle the action unless you made it straight blowback operation...and then it wouldn't be a 1911 any more.

rcmodel
August 17, 2012, 02:35 PM
http://www.jgsales.com/7.62x25-tokarev-barrel-kit,-5-inch,-for-1911-govt-models-in-9mm-or-38-super.-new,-by-j-g-sales.-p-5619.html

Be aware that the .38 Super mag will only hold six rounds.

And once you load it, plan on shooting it.
As the loaded round is too long to come out of the ejection port.

rc

Vern Humphrey
August 17, 2012, 02:44 PM
I count 6 rounds per magazine on that video, and note that they say the magazine will hold "4 to 8" rounds -- indicating you may experience feeding problems.

56hawk
August 17, 2012, 02:54 PM
I think you'd have a real problem getting it to cycle the action unless you made it straight blowback operation...and then it wouldn't be a 1911 any more.

Why do you say that? All the pistols I know of in 7.62x25 are recoil operated.

1911Tuner
August 17, 2012, 03:25 PM
Why do you say that? All the pistols I know of in 7.62x25 are recoil operated.

In a smaller pistol with a lot less mass in the slide.

Calculations show that the standard Tokarev cartridge (85 grains at 1250 fps) produces just over half the momentum of standard .45 hardball, and 3/4ths that of 9mm/124/1100. You might get it to work. Reliably? That's a tossup.

56hawk
August 17, 2012, 04:04 PM
In a smaller pistol with a lot less mass in the slide.

Calculations show that the standard Tokarev cartridge (85 grains at 1250 fps) produces just over half the momentum of standard .45 hardball, and 3/4ths that of 9mm/124/1100. You might get it to work. Reliably? That's a tossup.

1250 fps? That's some pretty light loads. Prvi advertises 1722 fps. http://www.midwayusa.com/product/761742/prvi-partizan-ammunition-762x25mm-tokarev-85-grain-full-metal-jacket-box-of-50 I load mine on the weak side at only 1450 fps since I also shoot it out of a C96 Mauser.

I'll have to weigh them when I get home, but I wouldn't be surprised if the CZ 52 slide weighed more than the 1911. Besides it's not that hard to lighten the slide or recoil springs in a 1911, but I doubt it would be necessary.

el Godfather
August 17, 2012, 05:10 PM
I will buy it for sure!

2wheels
August 17, 2012, 05:16 PM
.38 Super 1911s are awesome. .22LR "1911s" are great for training. Even 9mm 1911s are ok... (Ok I lied, my EMP 9 is awesome). And that .22TCM 1911 looks interesting.

So I think we 1911 faithful can live with a 7.62x25 1911. I'd own one.

I was gonna mention that conversion kit, but RC beat me to it. Never talked to anyone who owns one.

1911Tuner
August 17, 2012, 05:18 PM
*shrug*

Give it a try. Shouldn't be too hard. A slide with 9mm breechface dimensions and a barrel chambered for it.

I remember a 9mm round called the BAT. (Blitz Action Trauma) that consisted of a copper bullet with a huge hollow cavity and a hole drilled to blow off a plastic nose cap that weighed 85 grains driven to the furious velocity of 1650 fps. A friend of mine tried it in a 9mm Commander, and had short cycle issues until he dropped to an 8-pound recoil spring...and then he had failures to go to battery.

1700 fps? Forsooth! What are the pressure levels on that?

AK103K
August 17, 2012, 06:17 PM
Nothing new under the sun. Seems the VC beat you to it.. :)

http://www.ar15.com/archive/topic.html?b=5&f=49&t=104705

Legion489
August 17, 2012, 06:47 PM
Been there, done that. Works OK if you do it right and use a 9mm/.38 Super slide. Got the idea from a friend who had a VC made copy in 7.62x25. There are all sorts of cartridges sold overseas too. Colt made (makes?) a .30 Luger model for Europe, along with several other cartridges, but they are not sold in the US for whatever reason.

Mizar
August 17, 2012, 06:56 PM
Tuner, a TT33 slide weights about the same as a commander slide. The muzzle velocity of a standard Russian 85 grains ball ammo is about 1400 fps. A pistol in that caliber definitely needs a locking system for the barrel - Russian and Czech engineers (CZ52) are not stupid... Astra 400 is a straight blowback and the recoil of this pistol is not pleasant at all. Not to mention the ridiculously heavy recoil spring. I remember a conversation with you here on THR when you calculated the recoil impulse of 7.62x25 to be roughly the same as .38 Super.

Boris

P.S. I highly doubt that the mentioned BAT round gives 1650 fps in a commander length barrel - there is not enough room for the powder in a 9x19 case.

bluethunder1962
August 17, 2012, 07:05 PM
I would buy one if it was from a good maker. I have thought the same thing with a revolver. I am not a gunsmith but it should be easy to do.

jj1962hemi
August 17, 2012, 07:09 PM
I'm a fan of this round and would be interested in more pistols of any kind in 7.62x25!

WardenWolf
August 17, 2012, 08:01 PM
I think you might need .38 Super or maybe 10mm to get the proper length, but you may be able to make it work. Mizar is correct. The Tokarev is pretty much identical in size and weight to a Combat Commander. There is nothing technically preventing the round from cycling the action. Only the length of the round creates a problem.

rcmodel
August 17, 2012, 08:06 PM
IMO: People won't be nearly as interested once all the cheap surplus ammo runs out.

rc

BCRider
August 17, 2012, 08:31 PM
Well, I guess my relative newbiness to shooting is showing. Despite having read all I can find on gun lore since I started out about 4 years back I'd never come across a 1911 in this chambering. Now it seems they are about as common as corn in the summer here in Chilliwack... And trust me... that is COMMON! ! !.... :D

We now return you to the usual battles over 9mm vs .45acp....

1911Tuner
August 17, 2012, 08:46 PM
I remember a conversation with you here on THR when you calculated the recoil impulse of 7.62x25 to be roughly the same as .38 Super.

It's not just the recoil impulse that determines it. It's more about the momentum, and the momentum generated by an 85-grain bullet is iffy.

Just going by the photos, the Tokarev's slide looks to be dimensionally close to the High Power's.

A guy over on 1911.org has been tinkering with a Commander-length 1911 chambered for .380 Auto. Even loaded to proof-level pressures, he can barely get the slide to move...and even with no recoil spring in the gun, it won't make it more than about 3/4ths of the way.

It may be doable with a 90 or 100-grain bullet loaded to 1500 fps, but that pesky question that keeps me from wasting time and money just keeps popping up.

"What is it for?"

If the object of the exercise is simply to see if it can be done, then by all means...carry on, and keep us posted. It'll be interesting.

You might be able to get a few pointers from Wild Bill Caldwell over on Pistolsmith.com. He's been tinkering with light, small caliber, warp speed cartridges in the 1911 for several years, and his efforts have been frustrating. He's blown a few magazines out the magwell, and the last I heard, he'd pretty much given up on the idea.

Vern Humphrey
August 17, 2012, 08:51 PM
Not enough momentum to cycle the slide? So go to a floating chamber.:evil:

For those who just tuned in, the floating chamber was Colt's answer to the problem of making a .22 LR cycle a M1911 slide.

Dentite
August 17, 2012, 08:53 PM
IMO: People won't be nearly as interested once all the cheap surplus ammo runs out.

rc


Which was about a year ago unfortunately. You might some old stuff floating around but nothing like the nice Yugo stuff that was $4 for 70 about two years ago.

rcmodel
August 17, 2012, 08:53 PM
My personal view is, it would be better to try to make a 1911 out of a Tokarev.
Then to try to make a Tokarev out of a 1911.

Better sights, some trigger work, new grips, and a positive safety would almost do it.
At least the magazines would be long enough to hold the ammo.

rc

Jim Watson
August 17, 2012, 08:58 PM
I've read most of the material on the subject.
If four in a magazine are enough, fine, it actually feeds, fires, AND FUNCTIONS.
The conversion apparently functions fully loaded if you deep seat and recrimp the bullets so they fit a .38 Super magazine. Of course those nasty craters in the primers might be trying to tell you something.

If you want the round and not just the opportunity to plink with Iron Curtain Surplus, handloads with blunt bullets have no drawbacks.

But at that point, I'd go with a 9x23 and light bullets at screaming velocity.

SharpsDressedMan
August 17, 2012, 09:27 PM
I'd like to see it, only necked down to .224. That would be a great varmint round.

bigfatdave
August 17, 2012, 09:39 PM
I'd like to see it, only necked down to .224.
http://www.thetruthaboutguns.com/2011/11/foghorn/ria-introduces-first-production-22-tcm-firearm/
http://1.bp.blogspot.com/-WeLzM-LUA1M/TkYaHX9Sn0I/AAAAAAAAATo/MbYhCfa69Nw/s1600/.22+tcm+comparison.jpg
http://the-zombie-hunter.blogspot.com/2011/08/small-bullet-bit-hit-new-armscor-22-tcm.html

Armscor makes it, they call it the TCM (Tuason / Craig Micromagnum) and markets it here in the US under the Rock Island Armory banner.
It is a pretty slick design, only limited by a single source of magazines and ammunition, which would be a deal-breaker for me except that it comes with a 9x19 conversion kit in the box, which is RIA solid and even runs steel-case junk ammo.

So buy one, and order a bunch of ammo ... I'd like for the TCM round to not die like so many wildcat cartridges, and I'd like to see more variety in ammo types in this chambering.

barnbwt
August 17, 2012, 10:20 PM
For those who just tuned in, the floating chamber was Colt's answer to the problem of making a .22 LR cycle a M1911 slide.

I don't think that will quite be necessary for a round as nasty as the Tok. I had to put a heavy-ass 16lb recoil spring on my CZ to tame the frame smack. Took me three tries to rack it the first time (I swear, there was oil on my hands :o). The CZ doesn't exactly have a light slide or barrel, either.

1700 fps? Forsooth! What are the pressure levels on that?

Just a hair over 34000psi, if I recall correctly...

The 7.62 is basically a Mauser .30 Magnum ---only the Czechs didn't feel the need to make the round dimensionally different than broomhandle ammo for safety :uhoh:. With proper bullets (not many options right now) the 7.62x25 is basically a lower-range 327Mag purpose-built for autoloaders. It also seems that .30cal hollow points perform quite well at these speeds, so the whole "overpenetration" thing the Tok is notorious for is now a non-issue.

There's even a .223Timbs sabot round based on the Tok that can get north of 2000ft/s, but isn't ballistically very stable (my guess is the twist is wrong for such a light bullet).

TCB

(is it me, or are there a lot of 7.62x25 threads around right now?)

Ky Larry
August 17, 2012, 10:39 PM
Smart people have figured out harder problems than these. If you can build it, then run it up the flag pole and see if anybody salute it. Good luck.

BCRider
August 17, 2012, 11:20 PM
It's fascinating to see the side tracks about so many truly obscure items that have been developed in the shooting world.

It just goes to show that even when there's lots of, and arguably too many, cartridges already that some will go out of their way to come up with something different that seems to solve their own perceived lack within the shooting world.

barnbwt
August 18, 2012, 01:32 AM
It just goes to show that even when there's lots of, and arguably too many, cartridges already that some will go out of their way to come up with something different that seems to solve their own perceived lack within the shooting world.

Yeah, let's all just shoot 9mm Glocks and .45 1911's...

Mizar
August 18, 2012, 04:36 AM
...The 7.62 is basically a Mauser .30 Magnum ---only the Czechs didn't feel the need to make the round dimensionally different than broomhandle ammo for safety... Actually the Russians "designed" the 7.62 Tokarev for the Tulski Tokarev pistol. Those guys really like to take an existing cartridge and "hot-rod" it - .25 Auto for the Korovin pistol, 9x19 for GsH 18/Grach, 9x18 PM for the PMM... They don't consider the same round dimensions to be a safety issue - those rounds are developed for government/military use - you put in your gun only what they give you. Those rounds were never meant to be commercially available to the public.

Tuner, seeing more than a few beaten to death TT 33s from somewhat moderate round count (2000 - 4000) I tend to think that there might be some serious momentum in that cartridge. The pistols in question were Russian wartime builds - Serbian, Hungarian and Chinese TTs are better. If you take a TT and a 1911 side by side you will find out that the TT is about 95% simmilar to the 1911. It was just engineered to be cheaper to produce.

Boris

1911Tuner
August 18, 2012, 05:19 AM
Well...Maybe it is doable. Looks like the main obstacle now is the cartridge overall length, which means either deep-seating or a shorter, lighter bullet...which then raises two problems. Excessive pressure or low momentum.

The first problem can be handled by reducing powder charges, which may then bring on the second. The second can be handled by increasing powder charges...but will it be enough?

And finally...if it can be made to work with a 50 or 60 grain bullet...what has been gained? A blunt, low-mass bullet would lose velocity and momentum rapidly, and about 25 yards out, the paper ballistics wouldn't be a whole lot better than a .22 Magnum fired from a rifle...if any.

The higher the initial velocity, the more rapid the velocity loss from the air's resistance. That pesky Newton 3 again. It shows up in the most unexpected places.

And finally...How would such a light, thin-skinned bullet hold up when it impacts the target? (Dangit Isaac! Sometimes I wish you'd just look the other way for a split second.)

Brin
August 18, 2012, 05:55 PM
Iím a fan of the 7.62x25mm round so let me put some misconceptions to rest. The 38 super maximum oal is 1.280. I reload my m57 tokarev with 32cal .312 dia 100 gr rnfp moly coated lead bullets with an oal of 1.280. The 100 gr hpís I use have an oal of 1270. You can put 8 of these rounds into a 38 super mag without any problems. Both the moly and the 100gr hp bullets are shorter than the standard 85 gr bullets so you donít have to worry about excessive pressure from seating them too deep. At 1400+ fps, there is more then enough energy to cycle the action on a 1911-38 super.

Hop this helps Dennis

1911Tuner
August 18, 2012, 06:42 PM
There's only one way to know. Somebody whip one up and put it to the test.

grendelbane
August 19, 2012, 07:19 AM
Barrels are already available. I have one, just haven't had time to install it yet.

That particuliar project is probably going on its second year.

Wild Bill Caldwell necked down a 9x23mm Winchester to .22, which makes my ears hurt just thinking about it.

Just because a project is not really practical is not a good reason for not attempting it.

1911Tuner
August 19, 2012, 09:49 AM
Just because a project is not really practical is not a good reason for not attempting it.

I reckon it's human nature to do it just because it's there. :D

AK103K
August 19, 2012, 11:17 AM
I reckon it's human nature to do it just because it's there. :D
Especially if theres lots of beer and a buddy or two involved. :D

Walkalong
August 19, 2012, 11:29 AM
Yeah, let's all just shoot 9mm Glocks and .45 1911's...Way too boring....... :)

The 7.62x25 MM barrel for the 1911 sounds like a fun project. That is all my .400 Corbon barrel is, a fun change of pace.

The 100 gr hp’s I use have an oal of 1270What bullet?

1911Tuner
August 19, 2012, 03:45 PM
Especially if theres lots of beer and a buddy or two involved.

Let's not go there.

The joke that goes: "Hold my beer and watch this!"

Well...I was that guy.

Brin
August 19, 2012, 04:06 PM
The only way the 7.62x25mm round will work in a modern day hand gun is if you reload it with rnfp or hp bullets. That is provided some one makes a conversion barrel, J&G sales makes a barrel for the 1911-38 super. Too bad they donít make a 7.62x 25 barrel for the CZ 38 super. It would be a great single action hand gun with a mag that holds 17 rounds or a 7.62x25 barrel for a Glock 20. Yes, I have tried some of my 100gr hp OAL 1.270 reloads in a Glock 20 mag and they fit no problem. 100gr hp and rnfp bullets are shorter than the standard 85gr rn bullets so you donít have to seat them deeper to fit in a 38 super or a glock 20 mag.

Max OAL of the 7.62x25 is 1.381".
Max OAL of the 10mm is 1.260"
Max OAL of the .38 Super is 1.280".
Max OAL of the .45 ACP is 1.275".
MAX OAL of a 100gr HP 7.62x25 is 1.270Ē
MAX OAL of a 100gr RNFP 7.62x25 is 1.280
Hope this sheds some new light on this subject.

Drail
August 19, 2012, 04:07 PM
Someone needs to stop smoking that stuff.

Zak Smith
August 19, 2012, 04:31 PM
Back when I was loading light for someone, I found that several compact and full-size 9mm pistols would operate OK at about 100 PF and at 90 PF with minor recoil spring changes. Based on this, I do not think there would be fundamental problems with the energy or momentum available to operate the pistol.

barnbwt
August 19, 2012, 11:10 PM
Someone needs to stop smoking that stuff.

Why? Bulgarian 7.62x25 smells like roses :D

The only way the 7.62x25mm round will work in a modern day hand gun is if you reload it with rnfp or hp bullets.

If I was going to carry a tok pistol for defense, I wouldn't want it any other way. The FMJs are just too dang unstoppable for sane civilian (and military, even) use. The high speed of the bullet just begs to be converted into expansion; otherwise it's completely wasted energy. Like the 5.7, I'll bet some clever solution can be devised to get a vest-penetrating round that still tumbles/expands out of the tok. Best of both worlds.:cool:

TCB

PS: Who's lame soviet job was it to tie all the tok ammo up in little packages? It's like the most pointless thing ever. Talk about squandered effort.

Auto426
August 19, 2012, 11:51 PM
For those actually interested in this, it has been done before, and I'm not talking about the copies produced in Vietnam during the war.

In fact, it appears that J&G Sales is still selling them: Clicky (http://www.jgsales.com/7.62x25-tokarev-barrel-kit,-5-inch,-for-1911-govt-models-in-9mm-or-38-super.-new,-by-j-g-sales.-p-5619.html)

Looks like you need to start with a .38 Super or 9mm 1911 with a non-ramped barrel, install the new barrel and bushing, and then swap the recoil spring for the appropriate one. It also seems that .38 Super magazines will work with 7.62x25 rounds, eliminating the need for special mags.

Jim Watson
August 19, 2012, 11:55 PM
There is no need to speculate, it has been done.

But a standard .38 Super magazine will not load full of GI 7.62.

Numrich has barrels for less than J&G but I am mystified as to why they offer three different catalog numbers with the same description.

I once looked at setting up a G.M. in 9mm Makarov and loaded some 9mm P to Mak ballistics; which functioned my gun. But apparently there was only one lot of heavy ball 9mm Mak imported and I did not think it worth fooling with for the standard stuff.

BCRider
August 20, 2012, 12:00 AM
Yep...

I followed the links provided early in this thread. Seems like it's simply a case of what colour one wishes to have.

Serves me right. Here I think I've come up with something SOOOO absurd that NO ONE COULD POSSIBLY have thought of it before.... only to find out that they are nearly as common as rocks.... :D

barnbwt
August 20, 2012, 11:58 PM
^^^^Yeah, you can just find them laying in the field;). I think a 1911 purposely chambered in tok would work great; it'd be as accurate as a CZ52 (with good barrel) but with a waaaay better trigger. I'd be more apprehensive of some Frankenstein hack-job conversion that only holds six (:rolleyes:) rounds.

Here I think I've come up with something SOOOO absurd that NO ONE COULD POSSIBLY have thought of it before...

The round is (was) fairly unknown to many folks. I've been hearing a lot more about it lately because everyone was talking about "defeating body armor" after carrot-cake did his thing. Now, chambering a 1911 in Gyrojet; now that's absurd :D

TCB

Fastcast
August 21, 2012, 12:02 PM
Hell, just go through some of the surplus 7.62x25 if you need shorter OAL to get it to work.

The surplus I've purchased is all over the place in OAL 1.380-1.280 :rolleyes:

I don't even mess with the stuff any more, I just buy S&B these days as it shoots out of my CZ52 like a red dot laser! :evil:

Wildbillz
August 21, 2012, 12:41 PM
Sometime back in the 80s, Navy Arms imported a bunch of US Army marked 1911's that had been converted to 7.62x25. A buddy of mine was thinking of getting one and trying to restore it to normal. He never did get it and they passed on in the surplus market.

WB

HisSoldier
August 21, 2012, 12:59 PM
My pastor was loading the round with a very light bullet to ridiculous velocities, rifle velocities. In a CZ52 he said he was on the bleeding edge, any more pressure and the case would burst (He had blown cases) and any less velocity and it wouldn't cycle.

The only reason for it has to be "just because", although his feats with long range pistol are quite remarkable. 1000 yards with a Thomson Center .223 that I couldn't do at 500 with a rifle.

Owen
August 21, 2012, 01:18 PM
It's not just the recoil impulse that determines it. It's more about the momentum, and the momentum generated by an 85-grain bullet is iffy.


Impulse and Momentum are equivalent.

1911Tuner
August 21, 2012, 01:35 PM
I dunno, owen. I've seen some strange things happen with extra-light bullets. Had a stock Combat Commander that short-cycled with an early lot of Glaser Safety Slugs until I dropped the recoil spring a couple pounds.

If memory serves me, that was...what...a 130-grain bullet at about 1400 f/s?

Owen
August 21, 2012, 10:55 PM
Tuner, its straight up math.

Impulse = momentum

Force x Time = Mass x Velocity

1911Tuner
August 22, 2012, 06:18 AM
I understand that, owen, but like our old friend Yogi mentioned:

"In theory, theory and practice are the same. In practice...they ain't."

Sometimes...there's somethin' that we fail to plug into the equation.

That 130-grain slug at 1400 fps should have had more than enough impulse/momentum to run that stock Commander...but it didn't.

Owen
August 22, 2012, 09:01 AM
It's not theory, its law. the law of conservation of Momentum.

A heavy bullet and a light bullet leaving the barrel with the mae momentum both experienced the same impulse. The impulse on the bullet is equal to the impulse on the slide barrel assembly. This is High School physics stuff.

1911Tuner
August 22, 2012, 11:08 AM
Not arguing that, owen. I said that I've seen strange things happen with light, high-speed bullets.

F'rinstance...

An Officer's Model that short-cycled with 185-grain hollowpoints, but didn't with 230 hollowpoints. According to the chronograph, the 185's impulse/momentum was higher than the 230's...but I still had short-cycle failures to eject with the 185s. When I went to 230s, the problems went away. When I went back to the 185s, they came back. Lather, rinse, repeat.

Jim Watson
August 22, 2012, 02:15 PM
High school physics is not adequate.

You not only have momentum, mass times velocity, you have acceleration. I am not qualified in Davis Mechanics but there is a school of thought that the rate of change in acceleration - fourth derivative - has physical significance.

And you have empirical observations from Tuner, but also from the people who have put 7.62 barrels in their .38 Supers and found the guns to function even with the light fast bullet.

1911Tuner
August 22, 2012, 02:23 PM
Jim, I have a couple of theories as to why I had the problems that I did. I won't throw'em out here, though. No sense in starting an argument. One of the things that crossed my mind is the difference in powder burn rate in the 185-grain round. There's impulse and there's impulse. Even with like muzzle velocities, the way those velocities are developed can produce some different results on the back end.

There's also the equal momentum thing. In theory, momentums are equal. In reality, they're only equal in the absence of outside force, or in the presence of equal outside force. With an autopistol, there's never an equal outside force. You can get close by removing the recoil spring, but the hammer or striker spring is still in play.

buckskinbob
August 22, 2012, 03:18 PM
I love my 1911s have a pre-war ACE that has a lightened slide and is recoil operated, not really a 1911 lock up. Ditto my series 70 service ace. both are to valuable for me to mess with. I had one in 9mm and traded it for another in 45, the several that i own
in 45 are either collectors or shooters. Thouhg none are sacred and get shot occasionally. I have yet to own a Super 38, I was close but this orphan bromhandle came along. the adooption papers were expensive so the super is on hold. 20-20 hindsite says if I'd kept the 9 I could have just swapped the bbl.
will the Tok head diameter be close enough to use that slide ? I sure hope that you build it and more important Enjoy It !!!

Owen
August 22, 2012, 04:14 PM
High school physics is not adequate

Yes it is. Verified with High Speed Video.

grendelbane
August 22, 2012, 07:08 PM
Remember, the bullet is not the only thing being ejected. The burning powder produces a gas which still weighs as much as it did when it was a solid. And, it is moving fast, faster than the bullet does.

Some cartridges are louder than others. Because the pressure of the burning powder is higher than in other cartridges. Or, in shorter barrels, the same thing holds true.

7.62 Tok is a loud cartridge, those gasses are moving quickly when they leave the barrel.

1911Tuner
August 23, 2012, 05:51 AM
Yes it is. Verified with High Speed Video.

And yet, I still had short-cycle problems with light, screamin' velocity bullets that should have produced greater impulse and momentum than the heavier, slower ones. That's evidence that there's a little more in play here than simple action and reaction.

barnbwt
August 24, 2012, 09:46 PM
You not only have momentum, mass times velocity, you have acceleration. I am not qualified in Davis Mechanics but there is a school of thought that the rate of change in acceleration - fourth derivative - has physical significance.


It's called "jerk," and I believe it affects how energy is dissipated through heat when metal deforms ("elastically" or plastically). I think (very vague memory here) that it can affect spring stiffness(that may only be in large springs, though). There's also friction forces that are harder to pin down; in a larger-caliber platform (like the 1911) there may be more friction going on with the (larger) bearing surfaces than in a lighter-built gun.

Most likely, though, it's all pressure-spike distribution; if the Tok round burns it's juice off while the gun is in lockup, a larger share of it's energy is spent pushing metal into metal, when the mechanical advantage of the recoil is low. A longer duration burn (like the .45) gives enough boost to unlock the action, plus some residual pressure to push the action back when mechanical advantage is a bit better. Obviously this effect would vary greatly from pistol-model to pistol-model, and would be much more pronounced with a lower recoiling, faster round like the Tok. That could explain the mixed results people report.

TCB

Jaymo
August 24, 2012, 11:00 PM
I'm with Tuner and Barnbwt on this one. In theory, different weight/velocity rounds with equal recoil impulse will work the same.
In practice, they don't.
Not only do you have different burn/recoil durations due to bullet weight and powder burn rate, you also have increased friction with the longer/heavier bullet. That increased bearing surface also increases the pressure duration and recoil impulse duration.

Did I explain that well enough? I had a pretty bad wreck today, at work, and the pain meds are kicking in. Explaining things is not my strong suit, while under the influence.

Anyway, recoil energy is only part of the equation. Much like how gas pressure is only part of the equation in reliable cycling of gas operated autos.
Like how you can have two different loads with the same peak pressure, but one can be safe in a given gun and the other can be unsafe in the same gun, due to the difference in how fast they build pressure.

I have this nifty theory that recoil and blowback operated guns are actually gas operated, because it's the gas pressure that propels the bullet and creates the recoil impulse and blowback. According to my theory, the bullet is a gas piston.

We good?

BTW, my buddy and I have been talking for a good while about converting a .10mm or .38 Super EAA Witness and/or Para Ord into a Hicap 7.62x25.

Swampman
September 18, 2012, 10:39 AM
I know this is kind of an old thread, but in the interest of safety I wanted to address 56hawk's statement about the Privi Partizan claim of 1722 fps velocity for the 7.62x25.
Be advised that this is their claimed velocity from a 250 mm (9.84 inch smg) barrel.
Toks and CZ52s are generally good, safe weapons, until handloaders start to chase after velocities and power levels they were never designed for.

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