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7.62 x 25 Project

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floydthecat View Drop Down
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Post Options Post Options   Thanks (2) Thanks(2)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Apr 24 2022 at 6:03am
One often reads about a desire to shoot various bullet profiles from a 30-caliber carbine. The choices of what can be fired from the carbine action is limited by it's length and what will fit in the magazine and feed. The shorter length of the 7.62 x 25 facilitates the loading of various projectile weights and profiles. The case capacity is about 80% of the 7.62 x 33, still plenty of room to load-up to 7.62 x 33 charges and not compress the charge. One can blow-up anything if they try, but using 80% full 7.62 x 33 charges in the TOK cases have shown no signs of over-pressure stress. If anything, it shoots a bit milder that Sellier & Bellot commercial loads. Pictured here are some 125-grain 300AAC pulled projectiles built to an OAL of 1.52. They feed and chamber well from a 30-caliber magazine. Also shown are some .223 cases after they are trimmed and ran thru the 7.62 x 25 sizing die. The issue with a re-chambered 30-caliber carbine barrel is the leade remaining in the chamber. The longer the OAL of the TOK load, the less this becomes a deterring factor. Necks can be left longer than the spec 7.62 x 25 case, which enhances tension and improves accuracy by taking-up the leade. I have not got around to any chrono work yet, been working on functional loads that deliver reasonable accuracy. The 110 and 125-grain loads have proven to be as accurate as the average 30-caliber carbine at the distances I have tested. The lighter 85-93 grain loads....not so much, but longer necks improve accuracy.

You might not gain much by building a 7.62 x 25 Tokarev to 7.62 x 33 performance, but it is a new playground that facilitates a much broader range of what you can shoot. The brass is easily made, it loads with the same components as the 7.62 x 33 and it's a great project for fighting boredom.




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35 Whelen View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 35 Whelen Quote  Post ReplyReply Direct Link To This Post Posted: Apr 24 2022 at 9:21pm
Originally posted by floydthecat floydthecat wrote:

One often reads about a desire to shoot various bullet profiles from a 30-caliber carbine. The choices of what can be fired from the carbine action is limited by it's length and what will fit in the magazine and feed. The shorter length of the 7.62 x 25 facilitates the loading of various projectile weights and profiles. The case capacity is about 80% of the 7.62 x 33, still plenty of room to load-up to 7.62 x 33 charges and not compress the charge. One can blow-up anything if they try, but using 80% full 7.62 x 33 charges in the TOK cases have shown no signs of over-pressure stress. If anything, it shoots a bit milder that Sellier & Bellot commercial loads. Pictured here are some 125-grain 300AAC pulled projectiles built to an OAL of 1.52. They feed and chamber well from a 30-caliber magazine. Also shown are some .223 cases after they are trimmed and ran thru the 7.62 x 25 sizing die. The issue with a re-chambered 30-caliber carbine barrel is the leade remaining in the chamber. The longer the OAL of the TOK load, the less this becomes a deterring factor. Necks can be left longer than the spec 7.62 x 25 case, which enhances tension and improves accuracy by taking-up the leade. I have not got around to any chrono work yet, been working on functional loads that deliver reasonable accuracy. The 110 and 125-grain loads have proven to be as accurate as the average 30-caliber carbine at the distances I have tested. The lighter 85-93 grain loads....not so much, but longer necks improve accuracy.

You might not gain much by building a 7.62 x 25 Tokarev to 7.62 x 33 performance, but it is a new playground that facilitates a much broader range of what you can shoot. The brass is easily made, it loads with the same components as the 7.62 x 33 and it's a great project for fighting boredom.





  Your post set my worn out mental gears in motion.

  I cut a .223/5.56 case off just behind the shoulder then trimmed it to 1.285". I then ran it into a 7.62x25 die until I had a neck at an arbitrary length, and VOILA'!! It's either a 7.62x25 Long, or a .30 Carbine BB (Big Brother)-






  Would it be possible to run the 7.62x25 reamer in further and create a longer chamber? I'm guessing that if the 7.62x25 feeds, then this one surely would since it's longer.

  I know there's not a lot of practical use, but the fatter case could potentially add another 100 fps, especially if the neck were kept short as in the 7.62x25, and brass is easily made out of abundant .223/5.56 brass. I should've formed the case with the same length neck as the Tok, I may do that tomorrow.

  Edit-

 I had to go outside to close the chicken coop, so while I was that close to the reloading room, I fixed it.

  

 And FYI water capacity of the larger case increased by exactly 2.0 grs. (21.6 gr. vs. 23.6 gr.) for a gain of roughly 10%.  
  


Edited by 35 Whelen - Apr 24 2022 at 9:42pm
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Post Options Post Options   Thanks (2) Thanks(2)   Quote Smokpole Quote  Post ReplyReply Direct Link To This Post Posted: Apr 24 2022 at 9:56pm
That looks almost identical to the .300 Blackout!
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Post Options Post Options   Thanks (2) Thanks(2)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Apr 25 2022 at 3:29am
I think you can form Tok brass from 300 Blackout just like you can 223. Haven’t tried that, but I took a different approach with the .223 brass. When I trimmed the neck off, I left the formed neck on the resized brass long, did not cut it back to 25mm. I left it close to 30mm, which is about as long as a 1.280 30-carbine case. I loaded-up some 93-grain projectiles, loaded and fired it. Put three holes from three shots on top of each other. It’s a god-awful looking round, but it feeds and takes-up all the excessive leade in the re-chambered 30-carbine barrel. It would literally almost print all the shots in the same hole if I could shoot them there.

OAL of the reformed case is not critical unless you make it longer than a carbine round. The TOK sizing die can create a neck as long as you care to make it and it chambers and feeds perfectly.

This way, you don’t have to create a new chamber, just leave the neck long. I will dig up a picture here soon. The real key to accuracy is leaving a long neck to cover the leade and it solves the neck-tension problem as well. None of this is likely to produce a round better than a 30-carbine, but it’s fun and facilitates the use of any number of bullet profiles and styles that can’t be fired from a 7.62 x 33 action. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 24 2022 at 3:39pm
Got around to testing some loads today. I settled on a +-75% full 30-carbine load using a mix of factory and my reformed .223 brass. The two powders used were H108 (AA#9 eq.) and W296. I tested some 110-grain X-treme plated bullets with OAL of 1.45 and some spire-point 125-grain 300AAC projectiles with OAL 1.55. Did not bother with the lighter factory 85-grain bullets….they are just not accurate from this re-chambered 30-Carbine barrel. I have also determined that accuracy for me is just as good as 30-carbine when loading the longer projectiles. 

10-gr. H108, 110-grain X-treme, mv 1650, pf 182

10-gr. H108, 125-grain Spitzer, mv 1722, pf 215

10.5-gr. W296, 110-grain X-treme, mv 1777, pf 195 

I mention power factor as a comparison to 30-carbine at 2,000fps, which works out to 220. Just as a measure of how bad I might be beating the carbine up. 

I generally load my 30-carbine stuff in the area of 1800fps. It won’t be much of a stretch to load the 7.62 x 25 up to that velocity.


Anyways……just information in case anyone is interested.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David Milisock Quote  Post ReplyReply Direct Link To This Post Posted: Sep 25 2022 at 10:05am
7.62 x 25 pressure is max 36, 250 PSI considerably less than the 40,000 to 44,000 PSI generated by full,power 30 Carbine. I'd check a calculator but my guess is the lesser pressure and the lesser bullet weight will generate less bolt thrust.

With the gas port location it may make cycling interesting. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 25 2022 at 11:04am
No cycling issues at all, but the “feel” is certainly more robust with stronger loads/heavier projectiles.  The greater the PF the greater the felt recoil. This carbine cycles commercial TOK ammo as well, I have not chrono’d any. You can tell from the ejection pattern and placement that it’s weaker, yet does cycle.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David Milisock Quote  Post ReplyReply Direct Link To This Post Posted: Sep 25 2022 at 12:24pm
Here's a bolt thrust calculation  formula link, https://en.m.wikipedia.org/wiki/Bolt_thrust#Calculating_bolt_thrust
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 25 2022 at 1:38pm
All that’s interesting, but it’s been 53-years since I had to depend on my math skills to get me thru algebra and physics in order to graduate from college and I’m not about to start all over again.

Felt recoil (power factor) and bolt thrust might not be directly and mathematically comparable, but it has to be a good indicator of the strength of what one is shooting, if only ballpark. Besides, PF is much easier to calculate😁.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sawbones Quote  Post ReplyReply Direct Link To This Post Posted: Sep 26 2022 at 10:47am
March 30, 2022 35 Whelen wrote:
"Nothing has approached the pain-in-the-butt factor of reloading like the 7.62x25, not even the 32-20, 38-40 or 44-40. It is very difficult to start seating a bullet straight and keep it straight with that short neck."

I presume this references cartridge concentricity.  If so, once the bullet is seated would it be reasonable to remedy "crooked seated" bullet w/ the Hornady Lock-N-Load Concentricity Tool?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 26 2022 at 11:05am
The projectile being used has a lot to do with it. I am loading the 110-grain carbine bullets as well as longer and heavier .308 projectiles. I completely understand seating the shorter 85-93 grain bullets can be problematic, but I am having no issues at all with seating using the longer projectiles and Lee dies. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 35 Whelen Quote  Post ReplyReply Direct Link To This Post Posted: Sep 26 2022 at 11:48am
Originally posted by Sawbones Sawbones wrote:


I presume this references cartridge concentricity.  If so, once the bullet is seated would it be reasonable to remedy "crooked seated" bullet w/ the Hornady Lock-N-Load Concentricity Tool?




   Yes, concentricity. The neck has to be flared to the point that there's practically no neck to hold the bullet straight. There are probably tools to mitigate this problem, but at least from the standpoint of a handgun cartridge it's not worth the effort, for me.
That said, I'm still watching this experiment with great interest.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 26 2022 at 1:37pm
I use the most minimal flare necessary to get the bullet to start. So much so that I occasionally crunch a case mouth, but the effort pays off in the long run. I agree that loading for pistol limited to a specific brass OAL can be more troublesome with the relatively short neck, but I have much better success loading even spec brass using longer projectiles. 

This configuration allows one to load and shoot any .308 projectile they are willing to try as long as cartridge OAL does not exceed what the magazine will accept and that’s 7.62 x 33 OAL. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David Milisock Quote  Post ReplyReply Direct Link To This Post Posted: Sep 27 2022 at 9:43am
Originally posted by Sawbones Sawbones wrote:

March 30, 2022 35 Whelen wrote:
"Nothing has approached the pain-in-the-butt factor of reloading like the 7.62x25, not even the 32-20, 38-40 or 44-40. It is very difficult to start seating a bullet straight and keep it straight with that short neck."

I presume this references cartridge concentricity.  If so, once the bullet is seated would it be reasonable to remedy "crooked seated" bullet w/ the Hornady Lock-N-Load Concentricity Tool?



Try the 357 Sig. What a PITA!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 27 2022 at 10:38am
I’ve been considering a SIG conversion. I have everything to do it but the chamber reamer, which I can rent. It would be another “thing just to do” and I have enough to play with right now.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David Milisock Quote  Post ReplyReply Direct Link To This Post Posted: Sep 27 2022 at 12:56pm
Originally posted by floydthecat floydthecat wrote:

I’ve been considering a SIG conversion. I have everything to do it but the chamber reamer, which I can rent. It would be another “thing just to do” and I have enough to play with right now.

You will be able to over power the mechanics of a 30 Carbine with 357 Sig loads. It operates at 40,000 PSI with U.S. loads and 44,000 PSI with European loads. I run European loads in my Glock 31 with 125 and 147 grain Hornady projectiles. 

Both of those loads will develop more bolt thrust than a 30 Carbine was designed to handle.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Sep 29 2022 at 8:20am
If one wanted a true wildcat, this would be the perfect gun to build one for. In forming brass, the shoulder could be moved out closer to the case mouth and the OAL could be as long as 33mm. The chamber has plenty of room to be deepened for a longer case shoulder placement. It would be fairly easy to develop something between 7.62 x 33 and 300AAC performance. The only limitation on loading would be not to exceed the proofing of the carbine action. I think 40-42,000psi would be safe enough. I am already close to 7.62 x 33 velocities with what I am shooting now loading less propellent. Another couple of grains might put it in 22-2300 muzzle velocity range.
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