The French 105mm was optimised to fire HEAT. It was non-STANAG standard. It utilised shallower grooves and a lower twist than the Vickers L7 and its derivative guns. It also utilised a specific HEAT round called "Opus-G" which had a teflon slip ring, which stop (well actually significantly decreased) the round from spinning. HEAT's effectiveness is decreased by spin, which is why most modern HEAT rounds are designed not to spin. However, in order to ensure accuracy at longer ranges, the round must have some spin imparted by the rifling, even if it is significantly lower than other rounds.
Anyway, NATO guns were designed primarily to fire kinetic energy rounds (AP/APDS), with HEAT or for the British HESH as a secondary round. So they retained their twist and deeper rifling. The French reversed that priority. While HEAT relies on chemical energy to penetrate, muzzle velocity becomes a secondary consideration as well. However, to ensure a flatter trajectory and faster time of flight (and hence ease the fire control computations), standard NATO 105mm guns fired their HEAT at a higher MV than the French.
With the development of long-rod penetraters, all that went by the wayside and HEAT and HESH were basically relegated very much to second-place as far as anti-armour use goes. Low pressure guns rely on them still, though.