In case you ever need to fight an army of watermelon people, you might want to pick up a fully automatic Saiga-12 shotgun.
The host of FPSRussia creates videos of various weapons he tests and modifies. He also occasionally pulls off some crazy stunts with those guns.
In this video, he demonstrates how effective his modified, fully automatic Saiga-12 is against the king of the watermelon men and light body armor.
Caution: The video includes some strong language.
A fully automatic shotgun is probably one of the most destructive and scary guns you can buy. No one would ever want to be on the receiving end of a shotgun spitting out 6 to 12 shells in a matter of seconds. Currently, the top two contenders on the market are the Saiga-12 and the AA-12 shotguns.
Besides the recoil issue the AA-12 seems to have solved, the Saiga-12 shotgun is a beast.