It turns out that Lex's Aircraft increases the base shells' range to 50, thanks for the heads up on getting me to double check my other mods. :D
In testing, the increased magazine range does make a slight difference, but the underlying issue persists even when removing all mods to just Hero Turrets, & Cannon Turret. It's as though the shots are automatically detonating when they hit 30-35 tiles regardless of turret range.
https://i.gyazo.com/2d53826cbd729c0ddd3e405a50d7ffa1.gif
Highlighted turret has range of 56 tiles
https://mods.factorio.com/mod/HeroTurretRedux
Hope this info is helpful.
Edit: I don't have space age, so can't test the quality variations.