Gentelmen, "never" is a word that shouldnt be used unless your %100 sure that your right. Let me blind you with the light of truth.....

The source: The Great Book of World War Two Airplanes
Authors: Jeffery L. Ethel, Robert Grinsell, Roger Freeman, David A. Anderson, Fredrick A. Johnsen, Alex Vanags-Baginskis, and Robert C. Mikesh.
from Bonanza Books
The Messerschmitt Bf-109 section is done by Author: Robert Grinsell.
His list acknowledgements are:
Gerhard Barkhorn
Wilhelm Batz
Adolf Galland

Gunther Rall

Erich Hartmann

Dietrich HraBak
Messerschmitt-Boelkow-Blohm, G.m.b.H
The Royal Air Force
United States Air Force
and list goes on and on.....
Now for the information....
Bare with me here it might be a bit lengthy...
The intial production batch of K-series aircraft to be delivered consisted of both the Bf-109K-2 and the Bf-109K-4 model. Powered by either the DB 605 ASC or DB 605 DC engines rated at 2,000 hp and incorporating the GM-1 boost system, the K-2 and K-4 modifications noted for the pre-production aircraft and standardized on the 30mm NOSE CANNON IN COMBINATION WITH A PAIR OF 15mm MG 151 MACHINE-GUNS.

The only difference in the two models was in the installation of a pressurized cockpit into the K-4 model.
With deliveries of the Bf 109K-2 and K-4 beginning in October, 1944, Messerschmitt undertook a further refinement of the basic K-series airframe to be used as a high-altitude bomber-interceptor. The designationassigned to this aircraft wsa the Bf-109K-6. THE AIRCRAFT WAS SIMILAR TO THE K-4, BUT REVERTED BACK TO THE 13mm MG 131 FUSELAGE MOUNTED MACHINE-GUNS AND WAS FITTED WITH A OAIR OF 30MM MK-108 CANNONS IN THE WINGS FOR ADDED FIREPOWER.
So, in hind sight, if the 109K-6 was similar to the K-4 but REVERTED back to the 13mm cowel guns. That would mean that the Me-109K-4 was armed with a Mk-108 or 103 30mm cannon and TWO 15mm MG151 mounted in the nose cowelings......
