During the Waters of Life quest after Colonel Autumn supposedly "dies", you can grab his belongings as long as he falls near the door. You must face directly towards the body with the cursor directly on the body in first person view. Once this is done, hold down the button that changes the perspective and you should be able to rotate the camera. Rotate the camera half-way and you should see a "Search Colonel Autumn" message. You can also search Dad and possibly everyone in the room if they fall close enough to the wall.
Colonel Autumn does not have his Laser Pistol until Take It Back!, at which point he swaps weapons. This being said, the only way to loot the 10mm Pistol without using the PC command console is to use the aforementioned camera glitch.
If playing on the PC, one can use the console command "TCL" to move through the door and loot belongings of everyone in the room. At any other point in the game the player may use the command console to generate a new gun.
If you have some spare pulse grenades with you then you can "move" the bodies closer to the door with careful use.
Some players have found that looting Colonel Autumn's body during Take It Back! does yield both the 10mm and Laser Pistol he is intended to use during that quest. Unfortunately, this means that you must install Broken Steel or purposely not complete the main quest to use them. There is, however, no way of knowing whether the 10mm will be present on his body.