I understand wanting the vehicle Tesla cannon to have better/different stats than the handheld/turret variants, but could this not have been done through the Turret, rather than the ammo? From what I can tell, you can define your own chain inside the attack_parameters.ammo_type for the vehicle gun itself. Granted, I don't know how that's going to work for an ammo-using weapon when the ammo already has its own effects defined... Might inherit both. That's if you really want the different arcing behaviour, though (12@30% vanilla vs. 15@10% for yours). If you just want to alter damage, you can do that through attack_parameters.damage_modifier.

The reason I'm asking is that right now, you're effectively duplicating the Tesla Ammo item solely for your own vehicle, which introduces duplicate logistics. I'm wondering if there's a way to reduce the duplication by altering the gun and just using vanilla Tesla Ammo in the vehicle - same as the various Cannon Turret mods just use preexisting Tank Shells.