It looks weird when you do the glitch its like you got a Bon@# with the tactical insertion.
1. Have a class with One Man Army Pro and tactical insertion
2. Take out One Man Army and hold over the class with the equipment you want to do the glitch with
3. Press B and go back.
4. Hit Y, and right before the class menu pops up, use your tactical insertion, and quickly change class with One Man Army while you are planting the insertion.
Zero!