IK3, just because there's more than one ammo option doesn't mean that the others need to be perked. For example, the Mossie has an "overload" option that loads more ammo, but this was common. The P38 has an option with 500rpg for the 30cals, but this was normal. The P47s have an 8-gun option that would take you a year to count every round in the belts, but this was the norm. The lighter loads were done by the pilots, for various reasons.
So just saying "perk the higher ammo count" isn't right. The higher ammo count is more often the more common one.
Somebody mentioned in the main forum "perking the 190a8 with 30mms" -- only a LOT of the A8s had 30mms, they were common place, as they were shooting bombers down.
I hope HTC perks weapons setups judiciously, and not willy-nilly. C-hog cannons, definitely yes. 109 extra ammo, definitely no. 190 30mms, definitely no, LA7 3-gun option, small perk (I hope).
Most planes in AH don't have perkable arming options.