I am wondering this because I can shoot my Plasma Pistol 6 times with my full AP (120-135 iirc) while laser rifle only twice and ofc for a lot less dmg.

Does anyone know how to calculate AP cost per use of a weapon and how do mods affect this ?

EDIT: is this actually connected to weight? Does weight equals AP per use??? It would mean that for VATS users weight is important DMG wise and for non-VATS users fire rate is better.

Dont know full AP cost formula but it isnt pure weight per se, but perhaps class of weapon instead - with bulkier weapons that weigh more use more AP

If simple pure weight was a variable, then adding mods that increase weight would imcrease AP per shot as well. And on my ever increasing 10MM pistol as I upgraded it, did not notice AP use go up.

so cant say 100% as did not explicitly test, but havent noticed loss of shots per max AP bar when increasing weapon weight due to mods.

as a guess for now, i would say AP per shot is based on weapon type

The formulae is more complex than just weight. Bulk, rate of fire, auto vs single fire, ammo type plus more factors, all goes into factoring AP of a particular weapon. Dunno why they haven't included the AP stats for weapons. Perhaps it is a reflection on how shooter like the game is, where VATS supposedly play a minor role compared to FO3 and FONV.

So when does a pistol become a rifle and changes its type then ? I wish they would include AP cost stat too.

I also feel VATS plays even bigger role than previously. Maybe because it's the first time I am playing Fallout on console instead of PC ;p