Z model with phosphorus sights?

[MikeT]

As issued Yugo that I recently removed from cosmo.

The sights on my are the phosphorus paint, but data I’ve looked into suggest it should be tritium.

Any thoughts on this?

[Greasemonkey]

There is no hard firm phosphorus end vs tritium start serial suffix. Early models have been found and noted with tritium. There have been some that have had both styles.

This link takes you to a serial chart that was done years ago, it covers many serial prefixes.
https://sks-files.com/index.php?topic=1489.0

[MikeT]

Thank you for this.

[Witchywoman]

Cannot see the sight well in pictures but it reminds me of a set of AK clip on night sights I used to have. Most were glow in the dark but the polish had a tritium version too. Unrelated to the SKS though.

[running-man]

Rear sights in his photo are definitely phosphor paint sights.  They are on the standard flip up grenade sights seen across M59/66A1 production.  The tritium vials do pop up from time to time in M59/66s produced before the Z series (1986), but I think from the scattered data it's pretty clear that those can be chalked up to replacements and were not installed during initial production. 

Here is the flip portion of the rear sight with the grenade sight flipped down:


Early S/N M59/66s with *no* night sights



Phosphor paint:


Tritium vials:

[Witchywoman]

surprised they still glow after all those decades.

[running-man]

They don't. Half-life of tritium is only 12.3 years. A gun built in 1970 with these sights would have undergone just over 4 half-lives and less than 6.25% of the original radioactive material would be left, far too weak to be effective.  Interestingly enough, the phosphor sights still work reasonably well if they are charged with an extra bright light source immediately prior to use.

The vials in the photo I posted were replaced with newly sourced tritium out of China. There was a nice thread on another board a long time ago detailing the process.  I'll see if i can dune find it...