I just played NMPD HQ and got 26 Headshot kills with just the sniper rifle and nothing happened. I didn’t get credit for Dome Inspecter which is for 15 headshot kills. I read somewhere that you had to use just the sniper rifle, carbine or beam rifle-the magnum doesn’t count. So I thought I was being safe getting all kills with the Sniper Rifle. But no luck.