[Pibwl]

One more thing: according to a quoted Russian article, the first Heat round for 100 mm D-10T gun - spinless 3BK5 / 3BK5M (according to Bronekllektsya, 390mm penetration) was introduced only in 1961. Also in Tekhnika i Vooruzhenie 10/2008 monograph on T-54 there is ammo for T-54A quoted: 20 HE, 14 AP, and Heat is mentioned only from 1961.

To make it complete, a Bronekollektsya monograph of T-55 claims, that in 1967 there appeared first sabot round 3BM10 (up to 290mm penetration - at 2km?), then only in 1980s: HEAT 3BK17M and sabot 3BM25.

Regards
Michal