The bug: Every time I switch from one to the other flamethrower, while the flames/the stream is still in the air, the following happens: The weapon slot is switched, but the fired projectiles not! Only the range of the selected weapon is used. This means that if I change from the short to the long flamethrower the vehicle does not start to fire the arc and continues to fire the direct flame (but with the range of the stream flamethrower). This works vice versa too.
To reproduce:
1.Have two Flamethrowers with different ammo types in your weaponslots of one vehicle
2. Shoot with the first one
3. While shooting with the stream still in the air, switch to the other one
Result: You will still fire the first stream, but it's consuming the second ammo and uses range and firingspeed of the second weapon.
Start shooting with the short range flamethrower...

...then switch weapons. I'd expect it to start firing like this:

But instead, this happens:

When you start shooting with the second weapon after the first stream landed completely, the second stream will fire like expected and intended.
This bug happens consistently with all ammo types that shoot stream-type projectiles, when fired from cars or the character.