sabot rounds on 7TP

[cbo]

IIRC "sabot" is sometimes used to represent rounds with very limited performance like the AP used in the French 37mm tank gun. Something about the performance of normal AP dropping off in a liniear fashion with range while sabot drops faster with range and thus is a better representation of a weak low velociy AP round that penetrates something at short range but not much at, say 500 meters.

Dont know if that is the reason?

The Germans were the first to use "sabot" in combat in the form of APCR in 1940, but experiments had been going on since the 1920ies, first with Gerlichs taper-bore hunting rifles, then with a cooperation between Larsen in Denmark, where Gerlich worked, and the French resulting in subcaliber rounds for the French 25mm anti-tank. Still experimental in 1940 and not issued, but IIRC the French shipped all their research to Britain and the US. Janacek in Czechslovakia also did some work on taper-bore guns, resulting in the Littlejohn adapter for the British 2-pdr later in the war. Don't know if the Poles ever worked on something similar, but they did experiment with some very powerfull rounds for their anti-tank rifles - IIRC they were full-caliber, though.