Armament for the K4 was 2 MG151 above engine and 1 MK108 or 103. It also had options for 2 210mm rocket tubes under wings or various bomb loads.
Actually, it's a pretty wide spread spec info deriving from the first generations of historians, which have been quoted again and again, but nowadays have been thoroughly proven to be false.
No Bf109 variant ever, mounted MG151 on the cowls.
Nor did they ever use a MK103.