SKS - bluing of receiver cover

[Umka]

I was recently looking at one SKS. Nice looking overall.
Receiver cover has different shades of bluing. I found similar looking picture (almost identical):

Should I be concerned about it? Is it wear off or some sort of arsenal re-bluing "job"?

 

[weasel1]

Looks like an arsenal job to me. I wouldn't be concerned about it. If it were mine I'd probably re-blue it. I'm sure it would bug me after a while.

 

[EL34/6L6]

I've seen many, many SKS ' like that.

 

[esque]

+1 Very common, has something to do
with the way they were heat treated.

 

[timandkimandshea]

Also present on Chinese versions. I idly wondered if it had anything to do with them being packed in the storage crates.
T

 

[agentcq]

Very common.

Seen on refurb'd and completely non-refurb'd rifles.

Yoopers and many sites thought for years that the discolouration was due to the storage crates.

After owning and unpacking multiple crates, the dividers do not touch this part of the receiver cover - so this doesn't explain the discolouration either. Dividers sit just rear of the receiver.

However we don't know when the crates we encounter were produced? They could have been stored in different crates during production and storage in the 1950's before mass refurbishment (taken place until the 1980's). Or perhaps storage racks at the arsenal or unit level had a part of the receiver cover resting on something?

Heat treatment might make sense also.

 

[Umka]

Thanks guys! Yeah now that I looked through webs about this "shading" - lots of sks pics have it :] guess I didn't pay attention before.

 

[Magellann]

Ive seen many with discolored covers as well, my theory is they may have restamped the star and date, then reblued as a touchup.