Seems redundant. Lets say I have a boomstick, and lets say I have an Annabelle. Just before the ammo regen time, I switch to my Annabelle and get 8 shots of ammo, and continue shooting with my boomstick.
As for weapons you find on the map. I will assume you are talking about a SMG, since they use SWEP.Primary.Ammo = "smg1" they will regen just like the automatics. However if they changed it be based on guns, coolz would have to add a custom regen for the smg1.