4 2cm in the Schrägwaffen position was proved to much. the whole understructure of the ehavy 4 eninge bomber was torn to pieces and the Do 217 crew suffered with falling debris. Reduction to two 2cm was powerful enough to do the job. the four mg's in the front were not enough, and with heavy arms the Do 217 was a lumbering truck just like the first He 219A-0's. too much of a good thing and then with all the experimentation of what 3m weapons to use in the undertray, wastage of this and the machines not to operative units, thusly only four 2cm's were needed as it had already been priven with the Ju 88G variants but it took the Nachtjagd too long to figure it out........