Talk:AtG Missile Mk. 2/@comment-25152732-20140708112842

If you have 15 (105% chance) of these you'll always fire three missles every shot. This item doesn't stack past 15. If you have 29 (203% chance) you still only fire three every shot. If a single shot pierces and hits multiple enemies it will only count as one proc and fire three missles.

So basically it works the same way as AtG mk. 1.