As memory serves both 30 and 50 BF109Es were called "Bf 109Ea" and it was the commercial variant of the a/c offered for sale.According to some books about Bf109 the Swiss Bfs were provided Switzerland with no armament,radio-sets and some parts of equipment in cockpits especially.The supplies started in April 1939 ( different infos found 14 or 17 April) and ended on the 27th April 1940.All aircrafts were sent to appointed workshops where they were licked into shape.The Swiss Bfs were equipped with two Swiss Oerlikon FF 20 mm cannons and two Swiss Oerlikon 7,45mm MGs.It has to be mentioned that Switzerland had bought ten Bf109D-1s before received E version.To be honest ,the Dora variant was the Cezar latest one.All Swiss Doras were armed with four Swiss Oerlikon 7,45 MGs ( 480 rounds on the each fuselage MG and 418 rounds on the wing MG )
The machine guns weren't Oerlikons (they only made 20mm cannon) but were a Furrer design known as the Fl.Mg.29. And their calibre wasn't 7.45mm but 7.5mm (they used the same 7.5x55 Swiss cartridge as the army's rifles and MGs).
Tony Williams: Military gun and ammunition website and discussion forum
All these aircrafts in fact were corresponed with E-3 variants. Swiss also ordered a licence for production in local Dornier-Werke plants (8 complete a/c were build as well 4 pair wings and 7 fuselages as a spare parts).