I calculated the empty mass for the Model 239 (based on AHT tables) equipped with 4*50 cals (Finns gradually replaced the fuselage mounted .30 cal with a .50 cal).
Equipped with 4*.50 cals:
Empty mass: 4363,4 lbs (pilot included)
Fuel (100%): 960 lbs
Oil: 68 lbs
Ammo: 215,3 lbs
Take off weight (full fuel and ammo): 5606,7 lbs
Weights with the .30 cal in place of the .50 can be found from AHT, .30 cal was the left fuselage weapon.