I just started playing Fallout 2 and I made a character with a high small guns levels, but is really hard to find guns in this game. I was searching for locations where I could find them. The http://fallout.wikia.com/wiki/10mm_pistol_(Fallout)#Fallout_2 in NukaPedia says that there's one at Rat Caves below Klamath. I searched but I couldn't find. Can somebody send me a link to a video or a printscreen showing where's the corpse w/ the gun. (Sorry for any mistakes, I'm from Brazil).

What I would do is head a few clicks to the town on south (Den) and arm myself there... that's what I usually do anyway.

The pistol you are looking for is hidden in a pile of bones.

The corpse is located in a dead end tunnel northwest of Keeng Ra'at's chamber, right next to the lower left entrance into the chamber. I'm trying to work a more precise description into http://www.falloutwiki.com/10mm_pistol_(Fallout)#Locations, but it's hard to do without pictures. Rough sketch:

| |___
| _*._| |
| | |
| |____| |
|__________Keeng__|

The * marks the tunnel where the pistol should be. If you left to rest and heal up, chances are the corpse has been removed by the engine and the gun is obscured by a pool of blood. No fix available, I'm afraid.