the ak 12 has the lowest fire rate of all ar's... The gun balance in this game is amazing compared to older games, you see people use nearly all the guns whereas in the other cods it was limited to like top 5 guns... so go away hater
Every CoD title changes the TTK. Just play more, eventually you'll adjust your timing.
Think of it this way. It's like the core player who gets hooked on HC. Eventually, he gets used to the timing of the game.
TTK for the best weapons in Ghosts is higher than MW2 and MW3. Also, MW2 had "gun issues" for its entire lifespan that were never fixed. So I dont think you really played that game.