ИM 3

[jstin2]

I have this SKS in my folder 1950 SKS with spike bayonet but I feel that this rifle should have its own post. I was concerned that it has a 45 degree gas port, but I have seen several 1949 with a 45 degree gas port although they were refurbished. Here are some folders with the pictures.
https://ibb.co/album/N9G70w
https://ibb.co/album/XyNBtN
Usually there is a matching number on bolt and carrier, but as you can see it is engraved and looks like a Q. ? Added more pictures.
https://ibb.co/album/Jnn1yB
https://ibb.co/album/9HYVWB
Now the stock has been refinished, but you can faintly see the original serial number and the cleaning rod hole is drilled and not channeled.
https://ibb.co/album/kgC8c7
https://ibb.co/album/yFk7sd
https://ibb.co/album/428Dt8

[Phosphorus32]

Very interesting extensively refurbished 1950 SKS-45. Thanks for sharing. ИМ is a known 1950 letter block.

[jstin2]

I am puzzled about the comment "extensively refurbished". Other than the stock being refinished (but original star, date and serial number can be seen faintly), I cannot see signs of refurbishment. Please enlighten me.

[Phosphorus32]

I am puzzled about the comment "extensively refurbished". Other than the stock being refinished (but original star, date and serial number can be seen faintly), I cannot see signs of refurbishment. Please enlighten me.

I was speaking in regard to an appearance perspective, so the replacement or redone stock. I can't see the original serial number in your photos due to the reflection but I'll take your word for it that it was sanded, refinished and restamped if you can see the arsenal, year, serial number and letter block.

[pcke2000]

I have this SKS in my folder 1950 SKS with spike bayonet but I feel that this rifle should have its own post. I was concerned that it has a 45 degree gas port, but I have seen several 1949 with a 45 degree gas port although they were refurbished. Here are some folders with the pictures.
https://ibb.co/album/N9G70w
https://ibb.co/album/XyNBtN
Usually there is a matching number on bolt and carrier, but as you can see it is engraved and looks like a Q.
https://ibb.co/album/Jnn1yB
Now the stock has been refinished, but you can faintly see the original serial number and the cleaning rod hole is drilled and not channeled.
https://ibb.co/album/kgC8c7
https://ibb.co/album/yFk7sd
https://ibb.co/album/428Dt8

Very interesting example, thank you so much for sharing. I guess another important question would be 'when did 90-degree gas port change to 45 degrees?'

[jstin2]

In my opinion the condition of the stock is a minor refurbishment. The major factors are refurb stamped on dust cover, painted metal parts and electo-penciled parts where it should be stamped.

[jstin2]

I also wondered if there were 1949 SKS's assembled with a 45 degree gas and that it was carried over in 1950. And once the 90 degree gas ports were expired they totally switched to a 45. With this serial number it should have been assembled in early January. I know that there are examples on early 1950's with a 90 degree gas port and that they continued forward with a blade bayonet. Is it possible that in late 1949 one or more assembly lines assembled their SKS with a 45 degree gas port and the others remained with a 90 degree gas port and it was carried over into 1950?

[running-man]

Anything is possible, including that this gun has been refurbished and parts such as the gas block were swapped at some point in time, this gun was assembled with leftover NOS parts as a 'one off', or that this gun is a '49 with a '50 cover.  Can't really say with much certainty with so few specimens unfortunately.  We can only keep collecting the data and see where it leads. 

I think it's impossible to assign a build date of January on a gun like this.  The evidence doesn't definitively point that way when we aren't even 100% certain it's not a '49 vs. a transitional '50

[jstin2]

Things we know about.
1 - Spike bayonets were authorized until Feb. 2nd 1950 or if the supply of spike bayonets expired before this date
2 - This rifle because of the stock ferrule shows that it was made for a spike bayonet.
3 - Eyelet latch pin has been found in 1949 and early 1950 SKS's.
Things that are in question.
1 - Are 45 degree gas ports found in 1949 SKS's?
2 - Is the serial number - ИM found in 1949 and / or 1950 production?
3 - Does the single line serial number on the cover mean anything? My other 50(EM 717 has 2 lines).
4 - Why would they replace the 90 degree gas port with a 45? They would have to remove front sight to get to gas port.

I have taken some more pictures of the gas port and the cover. You can see the vertical machine marks on cover.
https://ibb.co/album/tmPggz

[running-man]

Things we know about.
1 - Spike bayonets were authorized until Feb. 2nd 1950 or if the supply of spike bayonets expired before this date
2 - This rifle because of the stock ferrule shows that it was made for a spike bayonet.
3 - Eyelet latch pin has been found in 1949 and early 1950 SKS's.
Things that are in question.
1 - Are 45 degree gas ports found in 1949 SKS's?
Depends on your definition of a '49 SKS.  If the 90° gas block defines the '49, then no.  If like prefixes from uncertain date guns with similar feature sets are grouped into a certain year then yes.  Whether they are there due to refurbishment or original assembly is debatable, I tend to believe that any 45° gas block (or a curved gas block is theoretically possible I'd guess though I've never thought to look for one) on a gun prefixed with a '49 prefix is a replacement.
2 - Is the serial number - ИM found in 1949 and / or 1950 production?
Unknown.  This prefix definitely exists in 1954 and with 1953 Izhevsk.  Several refurbed examples with '49 to transitional '50 features exist and one or two have '50 covers like this one.  I don't think I've seen a '49 cover on one yet, but I think I only have 3 examples.  I do know that *all* of the '49 to transitional '50 featured carbines except this one have blade bayonets.
3 - Does the single line serial number on the cover mean anything? My other 50(EM 717 has 2 lines).
Means nothing, all originally marked single digit S/N are single line.  All originally marked double digit S/N are also single line. (see the '54 receiver cover AM49 below) Three and four digit is where the originally marked '49's and all Izhevsks have single lines whereas others have multiple lines.


Note that scrubbed and restamped markings need not follow this convention (though they might, depends on the refurbishment facility)  This refurb '52 is a good example of an outlier:


4 - Why would they replace the 90 degree gas port with a 45? They would have to remove front sight to get to gas port.
No idea why they did much of what they did.  Why do all the other '49 to '50 featured guns with ИM prefixes that I have in my files all have blade bayos and blade stock ferrules except this one?  It's an equal amount of work to go in that direction is it not?  Is it a lack or refurb, a one off modification, intermittent production perhaps even on dual lines like you mention, someone found a stash of OEM parts on the line, a rogue technician putting a pet project together?  I'm sure there are scenarios I haven't even considered yet, but they are still possibilities.  That's why I don't jump on the 'unrefurbished', 'unissued', 'unfired' bandwagon, I simply don't know.
I have taken some more pictures of the gas port and the cover. You can see the vertical machine marks on cover.

[jaroslav]

It has an EARLY 1949 magazine with a pin in the narrow part of the mag. Latter 1949 mags were made without the pin.

[jstin2]

jaroslav- Early 49's had no pin in the magazine and sometime in 49 a pin was added. This pin can be found on all later magazines.

[jstin2]

  I am wondering why the matching lettering on the bolt and carrier is not stamped with a number but what looks like a Q. The serial numbers on both are matching, ИM 3
https://ibb.co/album/Jnn1yB

 The only difference that I could find between my EM 717 and this one is the way the carrier was machined. EM 717 has a double pass whereas the ИM 3 has a single pass.
https://ibb.co/album/BzjQTj

[pcke2000]

  I am wondering why the matching lettering on the bolt and carrier is not stamped with a number but what looks like a Q. The serial numbers on both are matching, ИM 3
https://ibb.co/album/Jnn1yB

Interesting. To me, the 'Q' shape mark looks like a combination of multiple Cyrillic letters (something like OTK). An inspection stamp?

My 1949 bolt and bolt carrier are both stamped with a number '77' and both have a similar 'Q' shape mark.

[jstin2]

I checked my EM 717 and there are the matching numbers - 54, plus a O on the side. But on my ИM 3 there is only the Q.
https://ibb.co/album/mCzVrv

[jstin2]

pcke2000 - could you post a picture of your Q marking?

[jstin2]

I have raised the question of the strange markings on the bolt and carrier as it is usually a number.
https://ibb.co/album/0yH2wx
I have not received any response so I looked closer on my 2 early 50's. I found that the carrier grind is different. EM717 has a double pass where the ИM3 has a single pass.
https://ibb.co/album/BzjQTj
Then when looking at the end of bolt I noticed a few differences between the two.
EM717 has a rougher grind. Extra metal has been milled on the edges.
EM edge is 45 degree angle grind where ИM has a horizontal grind.
EM face has a horizontal grind. ИM has  vertical grind.
Stamp on firing pins looks different.
https://ibb.co/album/2SMFcX

[running-man]

I'd suspect there are no responses because nobody really knows.  It's all hypothesis.

The single vs two pass are clearly made by two different diameter endmills. 

Is that a formal change made at Tula after XX year or a personal preference of each machinist picking their own tool size? (As long as it was to print after coming off the machine it is typically good, sometimes speed is higher priority vs. surface finish or hitting tolerances dead nuts.)  Were Soviet machinists allowed this freedom to pick their own tool from the tool crib, or was it only done a single way?  Were setups universal or were machinists allowed to utilize their own (vertical vs horizontal) etc.

Could this feature be used to date a bolt/carrier/receiver/firing pin etc?  Unknown, not nearly enough data to even begin to answer that question.  Unfortunately, this opens pandora's box of skepticism with respect to the piece parts on each 'as-issued' or refurbished carbine: "Was this part original to the carbine when it came off the line?"  That's a *really* hard question to even begin to try and answer conclusively.  I've been at this since I got my first SKS in 2001 and I honestly have no idea how to resolve some of these questions.