Caution!!! Krastorio 2 is now available! Therefore Krastorio Legacy is no longer supported!
This mod expands the endgame, adds 30+ HR buildings, 60+ technologies, new ores, new items and rebalances almost all vanilla game content, making it harder.
Basically physical ammo in IR has a finite range of 18 because they're treated as actual projectiles. However, the Submachine Gun and various turrets in Krastorio have an increased range of 22, but don't modify the ammo range. This means you can be shooting at a spawner with a SMG at max gun range, but never inflict any damage because the bullets won't reach the target. Or your turrets can burn all your ammo shooting at spitters they can't actually hit.
I see someone else has tried a compatibility mod that could address this situation for the IR bullets (https://mods.factorio.com/mod/IRRangeConfig), but it looks like K's Imersite Ammo doesn't have a listed range, so posting here in case you wanted to make a more wholesome fix that keeps the ammo behavior consistent.