THE HOUSE OF THE DEAD: Remake

If you're using cheats, I'm not sure that it's possible to get this achievement with One Hit Kill turned on. Even using the Assault Rifle, I wasn't able to shoot an enemy enough before the screen would transition and keep moving. However, with the grenade launcher this achievement will unlock with the first enemy you kill, most likely. The grenade launcher with a direct hit will definitely unlock it. Refer to Full Armory (35G) for unlocking the grenade launcher, or just input the cheat code in the roadmap to get it. Then, just shoot any enemy with it and this achievement will unlock.