Ballistic Action Straight Bolt: Like a straight pull bolt, but using the same concept of an assault weapon, the gas from the bullet pushes the bolt back, reducing charge time by half.
Ballistic Knife: Russia still uses them, and it's always been a cool concept, a knife that by the push of a button, ejects with the velocity of a low grade bullet.
Gripped Bipod: Almost every military that uses LMGs has grips attached to the bipod, for dual action purposes.
Bouncing Betties: I dunno about you guys, but I like the idea of laying infantry mines that not only get headshots, but has a different blast trajectory than C4 or claymores.
Bomb Suit: If you're going to put some kind of stupid defensive item in the game that basically copies CoD, why not the bomb suit? Militaries the world over use this more than riot shields, which is more of a police item.