I assume that this achievement requires you to completely dismember five enemies. The best way is to use an assault rifle, such as the AK-47. As far as I can tell, this can be done on dead enemies. The points are:
- Head
- Left and Right Shoulder
- Left and Right Elbow
- Left and right thigh (basically where the leg attaches to the trunk of the body)
- Left and Right Knee
- Plant one in the groin, for luck.