Anyone know exactly how the lasersploder works?

I love this gun but recently I figured out that I really have no clue how the gun works mechanically. My main questions are how does ammo consumption work with it? (ie how much do you fire before it consumes a bullet. the gun seems crazy ammo efficient), How does amp damage work with it? (like does it apply it to beam or the projectile?), and does double penetrating prefix actually do anything other than consume more ammo?