How does attack MP gain work?

I known of the basics, but I'm wondering if there is a bonus gain on MP when you crit., and likewise a decrease when you gaze? It just feela like sometimes I get more MP when I crit., but I'm not attentive enough to notice. Maybe the more damage you do, the more MP gain?

I have also been wondering if you trigger "additional melee"... do you gain MP from that bonus attack as well? (On a side note, if additional melee is triggered, does your attack animation increase in duration as if you're literally doing an additional melee attack)?

*Using dual swords if any relevance*

 

Attack MP Recovery triggers for every HITTING auto-attack. Doesn't matter if it's a normal hit, crit, or graze, it gives the same amount of MP. Otherwise, if your auto-attack misses or gets evaded, you don't get any MP

For Dual Wielders, each auto-attack count for at least 2 hits, a perk exclusive to Dual Swords Users atm. xD

 

knuckle users can do it too with Aggravate
although it's random, since it doesn't trigger on every attack.

dagger users can also do it with Mail Breaker, but the chance is low.
shukuchi also adds a little extra ampr.

 

As far as I know, additional melee doesn't give mp at all. I haven't tested it in full or experimented around with it, but even if it did give mp, it's negligible.
Additional melee doesn't increase your animation duration, it just adds a ball spike explosion effect to your hit when activated.

 

No Ampr from additional stats

 

Do you guys know what's the ideal AMPR for any melee build (expect for dw)? Or is there a thread on here with that information?
Edit: nvm I found it here http://toramonline.com/index.php?threads/how-ampr-actually-works.16843/