one and half meter setup for CDG is quick shot, quickly press d pad back and forth to cycle through weapons and return the cursor to the current weapon, regular melee once to put enemy into CDG stun, then CDG. in total you spend half a bar for quick shot, and then one bar for the CDG
look at the 2nd method here https://www.youtube.com/watch?v=uLIAaAp-uCs&feature=youtu.be
this pretty much work with all regular weapons including machine guns except ammo box because you don't have enough time to step forward and do the regular melee. ada, helena ex, and piers ex all have short regular melee so they have to get really really close for their regular melee to connect, and they simply don't have enough time to do that if they use ammo box.
semi auto rifle can't do this either because the 2 hand melee will instantly kill the target after a quickshot.
but there are still some alternative for ada, helena ex, and piers ex. look at 30 seconds in the video, ada and helena ex have 2 hand weapons, they can just slide into opponent, cycle through weapons back to current weapon, then do the 2 hand melee, and then CDG. you spend 2 bars in total, but it's still a good deal. piers can also do back elbow, but it's hard to do that on moving enemies.
Ammo Box 50 is the weakest weapon in the game I agree with that.
What the video showed, if you were to use the Ammo Box 50 in those methods is not how you actually use it. Since I've used Default Ada and Helena EX for a very long time, these are the better methods to use.
On J'avos - 1.) Aim Ammo Box 50 on J'avo mask headshot so now they are dazed. That gives you free option to Slide then CDG for +7 seconds costs two stamina bars only.
2.) Aim Ammo Box 50 use about 1/4 bullets on J'avo then Counter for +10 seconds.
On Zombies - 1.) Default Ada's Ammo Box Counter type on zombies (grabbing) in Mining the Depths is a +10 seconds counter kill. In Catacombs, her counter type will make her invincible on Lantern zombies.
The best use for Ammo Box 50 is definitely for Default Ada at best due to the methods above and her counter type with it. With Piers EX and Helena EX they don't benefit much from it but the J'avo methods do apply. It's not actually garbage but it does have its uses. It is garbage in the sense if you want to shoot enemies with its ammo (like beginners do) and gets wasted.