410 carries less ammo and less total ordnance than the 110G.
Er... not so much.
The 20mm pair are almost the same loadout... While the 110G has a stock 2x30mm pair, the 410 can carry far superior Mk103 30mm with 150 rpg. Or it can carry 2x 20mm internally in the bomb bay, plus 2 externally, 200 rpg, for a total of 800 more 20mm rounds on top of the 700 internal. Or it can carry 4x 20mm internally (no drag) with 200 rpg, also 800 rds.
Or... just 21 rounds of 50mm.
The 410 can carry the same heavy ord as the 110, and has more combinations of ord. So ord isn't any different, but what IS different is it's all (except for 1 or 2 options) drag-free, and internal. Load that 110G down and all of a sudden you're 50mph slower than "clean" - but load the 410 down and it retains most of its top speed.
Also, keep in mind the 110G2 didn't get 30mm until much later. They removed their 7mm guns, flew 2x 20mm, added draggy gunpods to make it 4x20mm, until late 1943/well into 1944 when Mk108s were available. The Me210C (similar in performance and specs, thsi was the real basis for the 410 improvements, just a few mph slower) was operational in 1942. The Me410 was around in early 1943. It had better firepower for a longer time than the 110G did in the historical time line.
I'm not saying the 110G we have in-game is a slouch, I'm just saying as far as overall stories go, the 410 has the better firepower (overall)