The book I have says this on a Bf-110G-4 says this. They where primary used as night fighers and equiped with the Lichtenstein Radar. Armament was two 30mm Mk 108 cannons on top of nose and two 20mm MG 151/20 cannons mounted on the bottom.
The Bf-110G-4 Schrage Musik layout displays two variation to the normal installation. The two 20mm MGFF/M cannon are replaced by two 30mm MK 108 cannon, while the guns are aligned fore and aft instead of the normal lateral arrangement.
The rear gunner had a pair of 7.92mm MG81Z machine guns.
Source Walk Around Messerschmitt Bf-110G by Squadron/Signal publications
typical G-4 arms were thus and there was NO typical arrangement.
upper nose had 4 mg 17 and lower nose had two 2cm, this went as such in some units even into 1944
upper nose twin Mk 108 3cm cannon, lower nose two 2cm
upper nose twin MG 151/20 2cm long barrels with flash hiders fitted, two 2cm weapons in the lower nose.
the Schrägwaffen never had 3cm Mk 108 in the isntallation but only as a test. MG FF 2cm were installed as they could be easily rearmed with the round magazines and not having to belt feed them, something else for the poor rear gunner to have to look forward to
cut a way of what ? nose arms and what configuration or Schrägwaffen or ?
I have the official Bf 110G arms handbook with blue cover covering all the nose and belly arms details including the 3.7cm weapon a total joke to fly with, nasty on US bombers though . . . .
the cut a way is very old news back in the 1970's. 20 mm oerkilons are shown in the SM position with the hard to replace contained ammo drums. The caption is mismarked as 3cm mk 108's as Les pointed out. The schematic is one of a series done even in W. Greens bogus work on 3rd Reich planes years ago along with He 219A and the Ta 154.
As I mentioned a very nice handy small booklet in German is D. (Luft) T. 2110 G-2 Teil 8 A
Bf 110 G-2 Flugzeug-handbuch . . . . Schußwaffenlage
Ausgabe April 1943 covers the Bf 110G-2, G-3, G-4 and G-4/U 1.
55 pages jammed with line drawings which are excellent, info on the weapons and sights, electrical systems with these arms, within the cockpit layout, etc .....
To be precise: the caption states MK 108 with ammo drums, but the drawing shows MG/FF.
The drawing shows the rarely used MG 151/20 twin gun pack "M1", but doesn't show the radar scopes and SM gun sight.
Also interssting is the naming of FuG 212, as it also could be a late FuG 202.
And with all this equipment, it would be overloaded. This is a very impractical configuration, IMO.
Chris the config was used by NJG 1 for one unit, and you are right a real slow bird especially on the daylight missions against US heavies and of course was a sitting ripe plum for T-bolts and P-51's of the 354th fg