Author Topic: SKS Barrel/Receiver Index Numbers Identified and Verified  (Read 5889 times)

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Offline Greasemonkey

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #40 on: December 01, 2017, 09:38:56 PM »
 dance2

I don't wanna say it, but there is no other way to express my joy... We was right. :)  :P

Cross nation compatibility I can see.. how else would they do it with "licensed" copies. Would be interesting to try to verify.  If one looks, it wasn't until Russia and China didn't get along, did the SKS change to short lugs, press fit barrels, spike bayonets, their obligation to make it Russias way was gone. Like Yugoslavia, they did it their way, just faster, cheaper, and with less material.

I believe with Yugoslavia's past experience in arms building, Russia handed them a rifle and a spec sheet and said make this. They probably didn't need machines, setups and education to do it like the other nations. They had tons of machenry from WWII, How many years, like 30-40 plus, did they make Mausers and other weapons. They knew how to work with extractor cuts and head space stuff from building massive amounts of Mauser rifles. As long as they stuck to the Warsaw pact caliber 7.62x39, that was what was important, like Czechlosvokia and the Vz52/57 and the Vz58. The Yugoslavian Ak is another example of going against Russia's master Ak design.
« Last Edit: December 01, 2017, 11:33:51 PM by Greasemonkey »
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Online echo1

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #41 on: December 01, 2017, 10:54:20 PM »
Good Great job SKS junkies. PAX
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Offline dearclown

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #42 on: December 01, 2017, 11:08:03 PM »
Yes, I agree with your logic and think the interpretation in correct.

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #43 on: December 02, 2017, 12:00:11 AM »
I love this place. Awesome work!!!
RUSSIA SKS45: Tula 49, 50, 51 x2, 53 x2, 54, 57(И); Izhevsk 53, 54
POLAND SKS45: "W.P." Marked Tula 52
CHINA TYPE 56 CARBINE: /26\ 60 "S", 61, 64, 65, 66, 79; /UK5?\ 69; /256\ 70; /316\ 70; [0138] Stamped Receiver 70 x2; /306\ 71; /416\ 公安 73; /0412\ 78
CHINA Civilian: SKS-D (XZ), "SKS-D", Cdn Para x2
N. KOREA: T63
YUGO PAP M59: 66 C-Series x2; PAP M59/66a1: 73 J, 83 T
ALBANIA 561: 78

Searching: Romanian, German, Vietnamese, IC, and the rest...

Offline BARNAUL

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #44 on: December 02, 2017, 12:15:00 AM »
So tomorrow I will tell my wife,i can not put up the Christmas lights as I have to pull the stocks off my letter guns and check the alignment numbers !!!!!  Thank you,Again.
                                                                      BARNAUL

Offline martin08

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #45 on: December 02, 2017, 12:20:57 AM »
Yugo, North Korean and East German builders must have used a different  method.

No angular markings.

Offline Loose}{Cannon

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #46 on: December 02, 2017, 12:36:44 AM »
Yugo, North Korean and East German builders must have used a different  method.

No angular markings.

Likely tagged or ink marked, or simply numbered by bin.   thumb1
      
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Online Boris Badinov

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #47 on: December 02, 2017, 01:09:37 AM »
Yugo, North Korean and East German builders must have used a different  method.

No angular markings.

Likely tagged or ink marked, or simply numbered by bin.   thumb1

Yugoslavia probably put out maybe 15-30k a year total...ust below or just over a 3/4million total, right? And NK and EG couldnt have had too robust of an operation either, I would imagine.
Hang tags, numbered bins, ink or paint.

Seems as if the low production averages would allow for a more simplistic system of index-indentification. Less likelihood of mix ups.

Offline Loose}{Cannon

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #48 on: December 02, 2017, 03:07:53 AM »
iirc Yugoslavia only had two rework facilities.  This isn't like Russia or China having many small shops across a large territory.   The physical stamping of the components was likely not necessary for their system, but that (to me) does not indicate they didn't clock the thread timing on barrels and receivers. 
      
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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #49 on: December 02, 2017, 03:44:30 AM »
Neat!

So glad to see something explained with data...and pictures...
A theory transformed to fact, in short order, no less...once collected data, and a couple of guinea pigs were put to the knife wrench.

Just like that...questions become answers....and this locality proves its worth.......aaahhhhgaaaiiiin!

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Offline martin08

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #50 on: December 02, 2017, 07:16:52 AM »
Whether stamped in the steel or not on a Yugo and others,  calibrated male and female threaded jigs would quickly determine the index value if there was any question.

Offline firstchoice

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #51 on: December 02, 2017, 08:15:12 AM »
  Great job to all those that went to the trouble, effort, and expense of shaking out the facts here!  thumb1  clap1

  Not that it happens that often, but someone wanting to replace a barrel on a threaded barrel Chinese SKS now has the advantage of searching for a replacement barrel with an index number matching the host receiver. Like I said, it won't be a large scale of need, but it'd be a big help to use/know if you were changing out barrels.  thumb1

  Now, I'm curious to know what index numbers that my Chinese threaded barrel rifle use. Guess I'll have a pop-apart party this evening. I may even add a column in my log books for that info. I tend to lean to the OCD side, at times.  :)

  firstchoice

Offline KILLDOZER

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #52 on: December 02, 2017, 10:01:10 AM »
Cool thread, and nice work, guys !  thumb1

Offline SKS shooter

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #53 on: December 02, 2017, 11:03:12 AM »
Great thread and sorry I missed the vote!

My vote would have been yes.

This indexing method makes perfect sense for ease for of manufacturing for quickly matching receivers and barrels together that will easily time.
« Last Edit: December 03, 2017, 08:07:48 PM by SKS shooter »

Offline Loose}{Cannon

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #54 on: December 02, 2017, 11:12:23 AM »
If you really wanted to get anal about how this process was executed. We witnessed the barrels mating angle prior to torquing to be in the neighborhood of 20 to 30 degrees. Not only would they have clocked the timing of the male and female threads to establish the index point, they also would have either advanced the index value of the barrel jig, retarded the index value of the receiver jig, or both in order for the barrels to time somewhere between 20 and 30 degrees EARLY and that remaining amount of rotation to index is all torque.   thumb1
      
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Online Boris Badinov

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #55 on: December 02, 2017, 11:20:33 AM »
Thought on terminology.

I think it important to point out that, in modern firearm manufacturing the term "barrel indexing" refers to the process of determining the curvature of the bore and then indexing/aligning that curve with the vertical axis of the receiver-- with the curve opening up with the muzzle oriented either at 6 or 12 o'clock.

I think this process is a fairly recent development in the construction of high accuracy long range precision rifles.

But, in the initial "arsenal re-barreling" thread over in the Russian sub-forum, the term "barrel indexing" led me to some confusion in fully understanding the processes that were being described.

I realized finally that the indexing being referred to, likely had nothing to do with the alignment of bore curvature and vertical axis of the receiver.

Is vertical alignment of the barrel curvature possibly an aspect of the numbered pairings? And if not, might a refinement of the terminology be in order to mitigate the potential for confusion?


« Last Edit: December 02, 2017, 11:38:49 AM by Boris Badinov »

Offline Loose}{Cannon

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #56 on: December 02, 2017, 11:37:53 AM »
Its a loose term Boris, lets not over-complicate it.

https://en.wikipedia.org/wiki/Indexing_(motion)

Quote
Indexing in reference to motion is moving (or being moved) into a new position or location quickly and easily but also precisely. After a machine part has been indexed, its location is known to within a few hundredths of a millimeter (thousandths of an inch), or often even to within a few thousandths of a millimeter (ten-thousandths of an inch), despite the fact that no elaborate measuring or layout was needed to establish that location. Indexing is a necessary kind of motion in many areas of mechanical engineering and machining. A part that indexes, or can be indexed, is said to be indexable.

Usually when the word indexing is used, it refers specifically to rotation. That is, indexing is most often the quick and easy but precise rotation of a machine part through a certain known number of degrees. For example, Machinery's Handbook, 25th edition, in its section on milling machine indexing,[1] says, "Positioning a workpiece at a precise angle or interval of rotation for a machining operation is called indexing."[2] In addition to that most classic sense of the word, the swapping of one part for another, or other controlled movements, are also sometimes referred to as indexing, even if rotation is not the focus.
      
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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #57 on: December 02, 2017, 11:43:08 AM »
Not being a machinist, but having watched probably too many videos on rifle accuracy related topics, this is roughly the concept of barrel indexing I was working with...intially:

http://www.mwerksllc.com/barrelindexing.php

Barrel Indexing:

The concept of barrel indexing has been around for a number of years as a method of improving accuracy in rifles....

The majority of barrels, including custom made barrels, have a slight curve in the bore.  This curve is generally not considered a defect but normal to the barrel making process.  Barrel Indexing is the process of aligning the curve of the barrel to the vertical axis when mounted in the action.  In most cases the bore curve will be indexed  with the curve down orientation as this position usually provides the best accuracy. The orientation position could vary with a particular barrel.  With the barrel indexed in the vertical position the forces acting on the barrel by the bullet during its travel in the horizontal axis are minimized. With the use of a tuner the vertical component of the forces can be more easily modified improving repeatable accuracy performance.  Barrel tuners are commonly used on rim-fire bench rest rifles, and may mask the benefits of barrel indexing.  An indexed barrel used with a tuning device can improve the competitive features of an already competent rifle.  The beneficial affect of an indexed barrel should not be ignored.


Offline Loose}{Cannon

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #58 on: December 02, 2017, 11:54:22 AM »
In that example they are indexing the curve of the barrel to the vertical axis when mounted in the action.

In the sks world, were are referring to rotational indexing several premilled locations when torqued to the receiver as observed by witness marks.
« Last Edit: December 02, 2017, 12:22:35 PM by Loose}{Cannon »
      
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Offline Greasemonkey

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Re: SKS Barrel/Receiver Index Numbers Identified and Verified
« Reply #59 on: December 02, 2017, 12:30:47 PM »
I got to know.. think1  in a mass produced weapon, thats minute of man, designed for basic infantry with minimal training and maintenance and going to be used in harsh conditions, did a curve or barrel bow on the order of .001 make that much difference. Seems like a lot of effort for minimal gain, a target rifle, a sniper riifle yes, there would be a gain, but not a basic going to have the snot beat out of it and shot mercilessly on the battlefield, with a high probability of being lost in a ditch, in a pool of bodies rusting or some other fate.

The accuracy or durability gain would be minimal, if not a nil factor for the time and effort investment put into the task.

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