This constantly got me messed up when playing the Raptor, you expect a key to do X, but since your still switched to your ammo keys, it does Y.
I dont think the switching between the 2 is very elegant, especially in the heat of battle where you already have to manage a lot. I think a better solution would be a modifier key, like hold Shift + {1,2,3} to switch between ammo types and without is pilot tools.