What does that green line mean, their received accuracy ?
Yes
Wow! That's a valuable chart you put there. Sooo.... in english : If I attack from hugging distance it will be great (except i lose models quickly). If I attack from middle-far or far distance it's still ok. But if I attack from middle distance (aka 5-15), this won't be to smart. But from far distance aren't they still outclassed by rifles? They are, I'm pretty sure about it, the conclusion being the fact that I should still use them for hugging distance .
I wouldn't say 5 to 15 is middle.
0 to 15 is usually where close range weapons perform best.
20 to 35 is where long range weapons perform best.
Mid range weapons are weird in the sense that they do not have any range where they excel, they tend to be good at all ranges, so it fully depends on what they are fighting.
The following looks a bit weird, I know. Just look at it, then read what's written below, then look at it again. It's the DPS of a target squad divided by the Sturmpio DPS and then normed. The higher the value, the better is it for the Sturmpios to fight the targeted squad at that range. As usual it's not always worth it to fight at the best range if there is cover at an okayish range or if you have to close in under fire. Besides that keep in mind that 10 range is the magic number where cover gets ignored.
Vs Cons: 0 to 10 range is best.
Vs Con + PPsH41: 15 to 20
Vs Penal: 13 to 17
Vs Shocks: 30 to 35 range
Vs Riflemen: Anything below 15
Vs Riflemen + BAR: 10 to 15, but anything below 15 is okay
Vs Riflmen + M1919A6: The closer the better.
Vs Paratroopers + Thompson: 18 to 24
Edit: Added Paras with Thompson and Shock troops to emphasize that going closer is not always better.