Soviet Re-arsenal re-barreling?

[Greasemonkey]

I look at it who cares what the part was it's last time in a refurb shop. If it's close or beyond spec now, replace it. What it was... has no bearing on what it is now.

And who is to say the mismatched parts we see didn't come from truly broken rifles, broken receiver or something else. They scrap it out and keep the good bits.

How does one know the mark is not there.. do you or anyone else know exactly what every single Russian military stamp is and have verification of such proof. The stamp may well be there.....but no one knows exactly which one it is. And getting a Russian to come up off such information would be like China coming off their information....

And again.... why have no Russians been found with worn, pitted or nasty bores? Especially non chrome early ones?

[Boris Badinov]

The way I look at it, the rearsenal tech wasn't working with a complete gun.

If this were the case, then when the barreled action ended up on in the rearmorer's hands, he (or she) had to determine the re-serviceablity of the weapon without being able to test for function. The test for the barreled action was simple: Visual inspection, some basic spec measurments,  and slugging the barrel. If the barrel or receiver was worn or corroded, or some measurement out of spec, then  to the heap for smelting went the pair. With no way to test for function the re-serviceablity of the entire barreled action would have depended on the results of the inspection alone.

What would a re-barreling stamp look like? No idea. But since the soviets stamped for umpteen different procedures,  rebarreling would seem to be one procedure that would definitely require a stamp of some sort.

[Boris Badinov]

Replacing and/or upgrading stocks, triggers, magazines, and other parts are straightforward, and simplistic procedures (most of us can do this ourselves) in comparison to the time consuming tasks involved in replacing worn out barrels. Impossible? No. Impractical? IMO, absolutely yes.

See, I don't think that a repair arsenal with all the proper tooling would have that tough of a time replacing worn barrels.  They'd have presses and jigs to pull everything off on that old barrel in no time.  All the proper sized vises and spanner wrenches to pull barrels off easily too.  The headspacing would be the hardest thing to do I'd think.

You're 100% right about not seeing any evidence.  I haven't either, but again, it's not a feature that's captured very well in photographs and I wouldn't trust many SKS owners to be able to differentiate a chrome vs non chromed barrel.

This is a great discussion, as it makes us think!  Perhaps there is indeed a 'rebarrel' stamp that they used that we simply haven't deciphered yet.  There are lots of common marks on barrel lugs that could mean anything.  It might be worth trying to look for a pattern on heavy 'furb guns...

I Totally agree.

[Greasemonkey]

What's so hard about a rebarrel job for a refurb shop to do? Headspace.. they have head spaced hundreds, if not thousands. Thread the old one off, it will probably be close, set it up, drill a gas port in the correct place. The install the rear sight, barrel ferral and gas block, then front sight.

Maybe.... And I'm spitballing an idea..... Maybe, this is what the numbers on the receiver and barrel might mean..maybe they are all slightly different specs on each, maybe a .001 or .0005 difference in each. Maybe those are more than just a barrel/receiver assembly number. Each number could corospond to a certain measurement. So they go get a barrel with a number that matches what on the receiver, torque it down.. easy to put headspace in spec.

This is something that has never made much sense.. used by most makers...but no real rhyme or reason as to why....exactly. and why numbers don't exceed a certain number.

One never knows...

[Loose}{Cannon]

rebarreling would seem to be one procedure that would definitely require a stamp of some sort.

Then I guess I wanna see this 'rebarrel' stamp.   

We already have many known refurb marks.... Why would they stamp every part replaced with a special 'replaced' stamp?  They dont.  There are no 'replaced' stamps on FCGs, carriers, bolts, bayos, covers, mags...... nada.  The refurb mark is the rebarrel (and whatever else it got) stamp. 

The way I look at it, the rearsenal tech wasn't working with a complete gun.

But yet most refurbs still have their original non scrubbed parts after refurb....refurbs are not 100% franken guns. They had to be keeping parts together at some level. 

[Loose}{Cannon]

from CGN

I will say that the unpaired #2 that bobdbldr indentifies on the left side of his receiver is very intriguing, as the matched pair of numbers on the left receiver flat and barrel shank are known to be an indication of an original matching barreled receiver.

Dont we have dif fonts on receivers and barrels.... same gun?  I think RM just posted this somewhere....

If these numbers indicate what 'I' think they indicate...... its a seating depth indicator and the numbers were stamped prior to assembly. Match a 33 with a 33.... same insertion depth into the receiver as a 22 with a 22.  This would be vital in order to minimize headspacing tolerance.

[Loose}{Cannon]

http://sks-files.com/index.php?topic=3590.msg41242#msg41242

This whole paired numbers bs has irritated me since day 1.  Why do it in the first place??  Were they intending to later strip off all the barrels, mix them up, then put them back together again for craps and giggles??

The only reason I would think to remove the barrel is to replace it, and in that scenario you would be tossing the barrel so you dont even need a number on it.

My current theory of choice is that these numbers are fitment numbers used in the same manor as the barrel numbers for (what we think) to match up size wise to the RSB, gas block, stock ferrule, and FSB.

Basically it would represent a dimension of the threaded barrel socket of the receiver and visa/versa the threaded male shank and lug of the barrel. (lets say) the numbers represent a fraction of a millimeter. In this case the highest number observed would be .36mm which is just about .014 thousands of an inch.  I think its entirely possible to have a maximum tolerance variation across production of .014" or less. 

That being said when a worker milled a barrel shank, a dimension was measured. If the perfect target size is say 40mm and its over that number by .09mm  ....  its marked with a 9.

You do the same thing with the receiver, you can literally have barrels and receivers marked in bins ready to pull for a perfect match.  I would assume this measurement would be the barrel shank to mating flat so that the pair will index on the first attempt rather then having a worker failing to index barrels all day.

Put it this way....   RM may back me up on this one.

If you DONT do this during the production...

A: You have a high failure rate of indexing barrels
B: You have to mill the receiver face on nearly EVERY single receiver until index is achieved.

If B, welp.. then you end up with a LARGE tolerance range from gun to gun on the back end of the bolt requiring major differences in length for headspacing....  more time and milling and a VERY LOW probability of interchangeability.

No....  you do as I described in my previous post and avoid ALL of that.

You absolutely HAVE to devise a way to properly index lug flats and achieve consistent insertion depth into the receiver to ultimately save time, minimize drastic head spacing lengths of the bolt, achieve interchangeability, or at least reduce adjusting requirements of the bolt to head space.

[Boris Badinov]

Another explanation for the paired number that makes sense to me:

Prior to final assembly, bare-barrels were fully seated into the receivers, the alignment hash mark was stamped. Then--before removing the barrel to attach the ferrule, gas-port and front and rear sight blocks-- the matching numbers were stamped to assure that the now fitted pair of barrel and receiver were re-united when the barrel was reinserted for final assembly.

[running-man]

Hey Boris,

I always assumed that the stocks were XXX'd and replaced on different guns because that single part is the most time intensive part on the SKS and as such it was impractical to replace the same stock on the same rifle after a refurb.  By time intensive, I mean that it took many many hours, perhaps even days for all the processes to take place and for things to dry and cure properly before it could be handled and reinstalled.

Pull a stock off the rifle, remove all the metal components, strip it/sand it, hit it with at least one coat of shellac if not several with a fair amount of drying time in between, assign it to a rifle, fit the crosssbolt to the receiver correctly, sand internally as needed, check that the bayo cut is correct, and finally XXX and/or stamp it with the correct serial number.  I'd guess that many stocks were cracked and unsalvageable...off to the furnaces with those...which would mean there would be an equal number of blank hardwood and two crossbolt amber laminates on various guns indicating 'new' stocks coming into the equation.

I hadn't considered that perhaps the stocks are coming off guns that no longer exist...that's an interesting thought.  Would it be likely that stocks would outlast barrels though?  I have a hard time wrapping my head around that one, would a shot out gun have decent wood on it?  Maybe I'm being unduly influenced by the Sino-banians and how nice the bores are (albeit they are all chrome lined) and how poor (in many cases) the wood looks.  Good stuff though, I'm diggin' it!

[Loose}{Cannon]

Another explanation for the paired number that makes sense to me:

Prior to final assembly, bare-barrels were fully seated into the receivers, the alignment hash mark was stamped. Then--before removing the barrel to attach the ferrule, gas-port and front and rear sight blocks-- the matching numbers were stamped to assure that the now fitted pair of barrel and receiver were re-united when the barrel was reinserted for final assembly.

Two things..

#1  You have to install, index, drill, and pin the RSB, FSB, and gas block while in barreled receiver state.  Why?  Because the RSB houses the OP-rod which has to be perfectly indexed to the.... receiver. The gas-block then has to align with the RSB, and so then does the FSB!

#2  The lugs have a 'flat' on the top and bottom right?  Given machining length tolerance variations from lug face to chamber face, and receiver front to receiver headspacing lug.  You will NOT just be able to screw on any random barrel to random receiver and have the upper/lower lug flats index square to the receiver. You HAVE to have a controlled measurement/number system to mate barrels to receivers without executive over/under rotational indexing. 

I personally fitted a yugo barrel to a yugo receiver with non matching numbers. The flats did not index and the front face of the receiver had to be milled in order to rotate the barrel another 120 degrees. This also seated the barrel further into the receiver meaning ..... I had to do a good bit of material removal of the bottom rear of the bolt to headspace.  This is the kinda crap im talking about that is a HUGE no-no in mass production. 

[Loose}{Cannon]

Hell, I used to do all kinds of choppin and swapin on SKSs back in the day.... I fitted other barrels to non matching receivers on chinese aswell.  Im tellin ya....  .005 difference from lug mating face to chamber face or +/- .005 on the receiver mating face length.  You will not just screw that barrel in and have it index.

These numbers are a measurement control system for proper indexing and headspacing.

[Loose}{Cannon]

Do this....

Everyone go get out their russian sks and start looking for numbers on the barrel that corresponds to numbers on the RSB, FSB, and gasblock.

If anyone tells to their FSB has a #1 stamped on it so its more accurate then a #2 or a #3.....  Kick em in the ding ding.

I was a machinist in a past life.  Due to the human factor, machine calibration, tool wear etc you WILL have slightly larger or smaller IDs of components and ODs of the barrel journal locations where they reside.  You do not try 32 RSBs onto a barrel until you find one that fits.  You measure each ID and OD and mark them according to their measurements.  Example: RSB IDs measuring .726 to .730 are marked with a #1, .731 to .735 marked with a #2... So on and so forth.  These parts go into a bin separated by size #.  A worker assembling said components to the barrel will observe the OD measurement # stamped on the barrel near the RSB location and select the corresponding RSB from a bin of the same number. 

Proper fit everytime.... No guessing. 

Why do I post this?  Because an even more crucial component fitment requiring a similar system is the barrel/receiver.  These numbers are part of this process.

[Greasemonkey]

Yugoslavia did replace barrels at refurb. This is why refurbs, when supplied with a new log book, the book was empty. It was essentially new again, no issues, no wear. As the weapon entered service and got used, and inspected, parts replaced the book was filled out.  They used the log book for the life of the barrel or complete weapon, which ever came first.

Per the documents shown here:

http://sks-files.com/index.php?topic=1491.0

Did they use special stamps? Saying they are different than Russia is true, but in the end they were a communist nation, broke, scared and Russia would have stomped a hole in them. Up until Yugoslavia made the SKS, they were pretty much Mauser, they got all the details from Russia, like they did for the Tokarev. I'm sure Russia set them up on both how to build and refurb, the log books were like the M59/66, a Yugoslavian design. Yugoslavia was kind of more like the Czech Republic, did possibly the minimum of what Russia said, used the calibers set forth by the Warsaw pact and liked to tinker and be original.

So.. modern day Bosnia and the former old school Yugoslavian military did change out barrels.

Maybe cause there was no chrome, they had to rebarrel all the time....

[Boris Badinov]

And what is the explanation for the alignment hash mark?

There would seem to be no reason for it other than to re-align the barrel and receiver for a second time -- which would indicate that the barrel and receiver are separated after initial seating and indexing.

I will point out that no one of us knows for certain that exact order of operations for the assembly of the Soviet SKS. But that hash mark is on all of my rifles, Yugo, Romy, Soviet and Chinese. 

I see no reason for the cross-national persistence of the alignment hash mark other than to RE-align the barrel and receiver after they have been separated after initial seating/indexing/head-spacing.

This would make numeric pairing of the barrel and receiver crucial to ensuring that matched barrel/receiver pairs were reunited once rejoined. Hence the hash mark regularly appearing between the paired numbers: they are a triplet set:
Digits--hashmark--digits.

[Boris Badinov]

I was a machinist in a past life. 

Did you work machining, hardened Chrom-Moly Steel? Or with softer, more malleable metals? And in the production that requires as high a degree of precision as the manufacture of firearms? Because the differences are significant.

Not all types of machining are the same. And higher degrees of precision are required for certain purposes and procedures than for others-- for example,  inner diameters that differ by one to three thousandths  (like the barrel bore) are far more crucial than some outer diameters that can differ by several hundredths.


.

[Loose}{Cannon]

And what is the explanation for the alignment hash mark?

There would seem to be no reason for it other than to re-align the barrel and receiver for a second time -- which would indicate that the barrel and receiver are separated after initial seating and indexing.

I will point out that no one of us knows for certain that exact order of operations for the assembly of the Soviet SKS. But that hash mark is on all of my rifles, Yugo, Romy, Soviet and Chinese. 

I see no reason for the cross-national persistence of the alignment hash mark other than to RE-align the barrel and receiver after they have been separated after initial seating/indexing/head-spacing.

This would make numeric pairing of the barrel and receiver crucial to ensuring that matched barrel/receiver pairs were reunited once rejoined. Hence the hash mark regularly appearing between the paired numbers: they are a triplet set:
Digits--hashmark--digits.

I would tend to agree that the index mark itself would be used in the event a barrel was taken off and reinstalled for some reason. This in no way shape or form is evidence this was done at the factory, yet alone on every sks being assembled.  The marks are just a good habit for future reference. Most likely the only time they would be used is by a later smaller outfit if not a field armorer.

The index mark is literally nothing more then a reference point "if" the need arises.  I don't know just how much machining experience YOU have, but to suggest there be no measurement/numbering system and all barrels just slap on thar and index perfectly is NOT how this works by a long shot.

Could the numbers also be used to keep a barrel and receiver together on a small scale?  Sure... Call it two birds one stone, but on a large production scale you would alot more then 1-36.  Perhaps something like......  a serial number.   

You look at them thar barrel/component numbers? 

[Boris Badinov]

I promise to pull all of my Soviet guns from the safe this afternoon/evening.

Promise.

Finally got some decent weather, so I'm gonna try and get a decent 4-5 hour bike ride in be while the sun is out and the windchill isn't hovering near freezing.

[Loose}{Cannon]

Another reason I know the barrel was NOT removed to fit/install/index the barrel components is because the RSB covers the barrel lug flat.... How ya gonna put a wrench on thar?!?!.

While we are at it....  Go ahead and drive out those RSB pins on TWO russians or two chinese, drift them forward to gain access to the lug flats, bust those barrels off and swap them...... See if they index.  Be sure to have different numbers on the guns. 

Disclaimer:  I already know how this will end, but its a good learning experience. 

[Boris Badinov]

I would just like to point out that it is hazardous to claim outright that any one of us "knows" for certain the order of operation of any given part of a process that none of us were actually a part of.

I spent four years working (and one year as a shop steward) in a large scale industrial fabrication plant. There are many aspects to assembly line production that might seem to be counter-productive and counter-intuitive but which persist nonetheless. And there are any number of ways to explain why these seemingly less efficient apsects remain. None of us "were there."

And outright claims of certainty tend to place a dead end where a dead end might not exist.


...

Moving forward... Another inquiry:

Do we have any indications that might demonstrate that the barrels were blued before or after seating / indexing?

[Loose}{Cannon]

#1  Never have I claimed anything of the sort .  I just know for a fact you cannot index a barrel with the RSB in place, and you aint indexing a gasblock and FSB without the RSB attached and indexed FIRST.   Don't ask me if the rest of the receiver was assembled prior or after because I couldn't tell ya.

I gave you a fool-proof answer that literally covers every angle of the topic.  Don't be mad at me for it, your the one suggesting a receiver is thrown away when a barrel needs replaced and that barrels are fitted and removed dozens of times to find one that indexes or otherwise requires extensive additional milling procedures to make it index leaving you with a large headspace difference from one gun to another. 

Its just your/my opinion and which one makes sense is up to the reader.

The argument of 'your wrong because you were not there' is something I would expect to hear from someone having a failing argument.