The Martin Baltimore IIIA was the first version of the aircraft to be provided under lend-lease, and was armed with a different turret to the Baltimore III.
The turret used on the Baltimore IIIA was the Glenn Martin Type 250 CE 8. This was a low profile electrically powered turret, carrying two .50in Browning guns. This was a reliable and well armed turret that was eventually considered for use on the Halifax and Lancaster bombers, and was used on Liberators, Venturas and B-26 Marauders.
A total of 281 Baltimore IIIAs were produced, and they made up just under half of the 575 aircraft in the second British order for the Baltimore of June 1941. As lend-lease aircraft they were given the USAAF designation A-30, but the type did not enter American service.