DEFINITION:
Battlesight range in armored tank on tank warfare, is how far out you can hit an enemy-sized tank target without having to adjust for range. So it is about how flat your trajectory is.

DISCUSSION MADE
The discussion I saw was from Kev Sharp, positing that:
'T
he scoop from a former weapon effectiveness R&D analyst: The 105mm on the m1 was suitable to take out anything at up to 2000 m, with its fin stabilised round and velocity. The move to put the 120 in was political [ use the German gun, and use the British armour] to keep NATO members happy. The real impact was a 50% reduction in kill shot capacity [ammo].'

Clair Conzelman's rebuttal was:
'Not quite. I've shot both, and the 120mm has a flatter trajectory than the 105mm, and that is EVERYTHING in a big gun tank fight. To be able to battlesight rather than range each shot gives you that bare advantage and confidence you need in the ranges that most tank fights are fought at.'

CONCLUSION
The debate was centering on the belief that, i
t's about battlesight range rather than maximum range or penetration that makes a main tank gun superior.

Aaaaaaaand, Go.....