Anyone knows the relationship between AP, Fire Rate and the actual shots you can execute in V.A.T.S ???

Wish it was at simple as "AP-cost-per-VATS-shot" but it is not ...

Shorter barrels give you extra shots in VATS.

Shorter stocks give WAY more points in VATS for rifles.

Pistols have a ton of VATS shots.

Thank you Littlepip for your answer however I am looking for actual game mechanics calculations. Numbers if you want ...

Yep, they gives tons of informations but not even AP costs...

While in the same time damages are given twice in the pip boy inventory (in the weapon stats and on the lower right of the screen)...

Well, I dream of old school days of Fallout 1 and 2 when you could play with math equations and all kinds of numbers...
Still there should be a way to calculate and approximate stuff mathematically...