The two machines mounted adequate defensive firepower – four to six MG 151 cannon in the Ju 88 and six to seven in the Do 217 (the K variant possessed a twinned-up mount of 7.9mm MG 81Z machine guns in its nose)[40] – the confined space and 75-round magazines made it difficult to sustain concentrated fire against night fighters.[2] The close proximity of the crews in the cockpit, a feature of nearly all German bomber designs from the Ju 88A onwards, was also a disadvantage.