I don't know metric, but I had that converted to pounds and I got 3lbs. I know that this at gun had to weight more than 3 pounds, so your number is off. Tell us how many men would be needed to move a pak40.
76 mm divisional gun M1939 (USV) - Weigh combat:1,470 kg (3,240 lb) - On the photo 4 man, but I think under the gun there is one more person.
76 mm divisional gun M1942 (ZiS-3) - Weigh combat: 1,116 kg (2,460 lbs) - 6 man (full gun crew)
45 mm anti-tank gun M1942 (M-42) - Weigh combat: 625 kg (1,378 lbs) - 4 man out of 6 gun crew