Source for 20mm TNsH API-HV?

Been doing some deep research into BR 1.0 tanks for some suggestions I have in mind and cannot for the life of me find a reliable source for API HV found on the 20mm TNSh.

The 20mm ShVAK and 20mm B-20 guns feature identical AP belts, which differ +1/-1mm of penetration when compared to the TNSh across all listed ranges. I believe these to all be the same gun, ballistically speaking, and I believe these are all chambered identically, so I’m not sure what the penetration difference is from.

Regardless, the TNSh on the T-60 is the only 20mm from this whole family of guns to have access to 20mm API HV, penetrating 32mm of armor at 10m 0 degrees, it is unlike any other 20mm USSR belt.

Does anyone have any source for the existence of this API HV round or if there is a reason it isn’t available to any similarly chambered 20mm?

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@KillaKiwi might know more, as he generally went through the Shvak and TnSh.

There‘s an article on tankarchives about the round.
It was only experimental but wasn’t put into service.

I’ve tried searching their blog for TNSh and T-60 but can’t seem to find it, would you happen to have a link?

https://www.tankarchives.ca/2020/08/t-60-armament.html