The Ilya Muometz Type B initially carried an armament consisting of a 3,7 cm Hotchkiss cannon and a 8 mm Maxim machine gun.
Seven were built in 1914, first flight in June 1914.
I found in Gunstonīs book: Ilya Murometz-B: Only about four Ilya Murometz-B were built with two 135 hp and two 200 hp Salmson engines. Three of these machines were converted to carry 3 machine guns and 1,100 lb (= 500 kg) bomb load by December 1914.