Key point: In a way, it can be seen as comparable to the similar “budget” T-72B3 upgrade Russia has applied to its tank fleet, albeit less effective.
When the Cold War ended, the Polish Army inherited a massive fleet of T-72s. Most of these tanks were T-72Ms and T-72M1s, which were built in Poland beginning in the 1980s. In the 1990s, these tanks served as a valuable resource for Poland as modernization of the tank into the PT-91 “Twardy.” They also gave the Polish “Bumar” tank plant valuable experience in building their own T-72 upgrade, complete with domestic ERAWA ERA, passive night vision devices, and laser warning systems. The PT-91 also was an export success, scoring a major contract with Malaysia in the 2000s.
However, in addition to modernizing T-72s, Poland adopted the Leopard 2A4 and Leopard 2A5. Adopting Leopard 2s was the first step towards Westernizing the Polish tank fleet, but it split the ammunition supply chain for Polish tanks as the PT-91s and T-72s in Polish service still used 125mm guns. Bumar plant proposed a solution with the PT-16 and PT-17 tanks, which attempted to fit Western tank tech and a 120mm cannons onto the T-72. The goals of the project were to field a secondary frontline tank to the Leopard 2A4 and to keep the Polish tank industry alive.
A new 120mm cannon was the most difficult and critical part of both the PT-16 and PT-17 designs, as the 125mm cannon used on the T-72Ms was considered unsuitable for anti-tank usage. Advanced, high penetration 125mm ammunition is primarily made in Russia, which Poland cannot buy from for clear political reasons.
But most NATO 120mm ammunition is single piece, with the propellant and projectile unified in a single piece. Comparatively, the T-72 was designed to use two-piece ammunition, with the propellant and projectile stored separately. This means that the T-72’s autoloader must be extensively modified to use 120mm projectiles, or simply fully replaced.