SVT40 bolt colors?

[gunsaholic]

As stated in an earlier thread, I'm just getting into the milsurp thing. My foolish question is, why are there different colored bolts on some SVT40's? Is there any significance to this?

 

[CanadianAR]

Different refurbs at different times, with slightly different bluing solution or temps. Also the make up of the metal as well.

No functional difference.

 

[gunsaholic]

Figured it was probably something along those lines. Thanks!