Fritzie, as far as I can see, the E-1 was not cannon armed although there was provision for it. The E-2 mounted an MG-FF in the nose, but utilization of this weapon caused such severe airframe viabration that the E-2 series was quickly dropped after a very limited production run. I believe that the only ones delivered for actual service went to JG 26, but please don't quote me on that as I'm still researching. Following that, the E-3 through to E-9 had the capacity for an engine mounted cannon, but it was never utililized as far as I can tell. It was not until the introduction of the F series that the problems associated with an engine mounted cannon seem to have been resolved, and it was subsequently used on all following marks. If anyone has information to the contrary, please let us know.