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From Tallinn to Stockholm is 235 miles and from the Coast of Latvia (Liepaja) to Rostock Germany is 386 miles. Rostock is just over 80 miles from the current Polish border.
Russians didn't need bomb bay fuel tanks for most missions in the Baltic.
Also please remember that the A-20 could carry 140 gal in two tanks or 325 gal in three tanks in the upper bomb bay without affecting it's ability to carry bombs. These were self sealing tanks.
Four non-self sealing tanks could be fitted in the bomb bay (replacing bombs) for ferry purposes with 676 gallons and bring total allowable fuel to 1316 gallons. But since this is about 5500lbs of fuel over and above the 400 gallons in the wings ( and does not include the weight of the tanks) one might be excused for thinking that this option would not be used for combat even with external stores.
There was a Non-self sealing belly tank of 374 gals that fit on the bomb bay doors that was supposed to allow for the carriage of bombs while increasing total fuel load to 1199 gals (carriage of bombs may reduce fuel capacity.)
Weight of belly tank without fuel was 375lbs.
The upper bomb bay tanks rather take away the need for extra in wing tanks on the A-20.
You know me...
I don't know what allowed the higher weight ratings of the later models. Structural strengthening? different tires? different brakes? different landing gear struts?
Maybe just as well as the B-26 Marauders equipped with torpedoes performed at Midway.