The MS.300, a basic trainer, had a large gap between wing and fuselage and a wide track undercarriage, easing the progress of its novice pilots.
The tips were rounded and there was a deep cut-out in the trailing edge over the fuselage to improve the upward view from the forward cockpit.
The fuel tank, placed behind the engine firewall in the lower fuselage and between the undercarriage legs, could be jettisoned in flight in case of fire.
The in-flight adjustable, wire-braced, triangular tailplane was mounted on top of the fuselage frame, carrying balanced elevators.
The MS.300 had fixed, conventional landing gear with its mainwheels independently mounted on V-struts hinged to the lower fuselage, with vertical Messier oleo strut shock absorbers.
By early June 1930 the MS.300 had been entered into the rally organised by the Auvergne aero club, where it was to be piloted by Robert Morane,[3] but it was not reported as present the mid-July event.