All Oeffag variants were armed with two 8 mm (.315 in) Schwarzlose machine guns. In most aircraft, the guns were buried in the fuselage, where they were inaccessible to the pilot. In service, the Schwarzlose proved to be somewhat less reliable than the 7.92 mm (.312 in) LMG 08/15, mainly due to problems with the synchronization gear. The Schwarzlose also had a poor rate of fire until the 1916 model was provided with a modification developed by Ludwig Kral. At the request of pilots, the guns were relocated to the upper fuselage decking late in the series 253 production run. It helped to warm up the guns on high altitude. This created a new problem; the Schwarzlose operated via blowback and the weapon contained a cartridge oiler to prevent cases from sticking in the chamber while the extractor ripped their rims off. With guns mounted directly in front of the pilot, oil released during firing interfered with aim.