So apparently, you can't knife turrets in BO2.
Originally Posted by David Vonderhaar
You can't knife turrets in Black Ops 2 MP. It was destroying where they were they existed in the power/value band.
So basically, he has took out the ability to knife turrets since people would just take them out all the time like they were nothing.
I myself am kinda glad because I hated my turrets being ruined like right after I put them out, but I kinda hate it because I loved knifing people's turrets and listening to them freak out over it.
SOURCE: Twitter