The objection is the same as to any gun position which is fixed along the longitudinal axis of the aircraft: the pilot is forced to fly directly at the enemy in order to fire.
Under certain circumstances this is highly undesirable".
From the beginnings of practical flight possible military uses for aircraft were considered, although not all writers came to positive conclusions on the subject.
By 1913 military exercises in Britain, Germany, and France had confirmed the likely usefulness of aircraft for reconnaissance and surveillance, and this was seen by a few forward looking officers as implying the need to deter or destroy the enemy's reconnaissance machines.
And yet, "synchronization", in the usual sense of the word, between the rate of fire of a machine gun (firing as such, in a fully automatic manner) and the revolutions per minute of a spinning aircraft propeller is also a conceptual impossibility.There were in fact some advantages in dispensing with centrally mounted guns altogether.Nevertheless, the conclusive redundancy of synchronization gears did not finally come until the introduction of jet propulsion and the absence of a propeller for guns to be synchronized with.During the late-1930s, however, the main role of the fighter was increasingly seen as the destruction of large, all-metal bombers, for which the "traditional" light armament was inadequate.Since it was impractical to try to fit more than one or two extra guns in the limited space available in the front of a single-engine aircraft's fuselage, this led to an increasing proportion of the armament being mounted in the wings, firing outside the arc of the propeller.