the germans mounted 20mm guns on tanks and apcs, i wouldn't classify it as artillery. the croations developed a rifle in the 90's as a anti-vehicle/anti material rifle, fired a huge goddamned 20x110mm hispano round. the gun weighed a lil over 19 kilos though and the effective range was only supposed to be about 1800 meters the south africans also had the Mechem NTW-20 that fired a 20x83.5mm round however it had a three shot mag compared to the single shot of the RT-20.

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