My humble compilation of the awesome mod by trent1542 (all credits!!!)
Original mod is here http://www.fallout3nexus.com/downloads/file.php?id=8116
The idea belongs to my brother the great fun oh "THE BOOK OF ELI")))
I`ve just changed the stats of the weapon and reload animation

If Dr James thought about the fate of his child how would he help?
Maybe he left something for the future runaway to protect himself? Neither A-bomb nor machine gun only the 12 Caliber sawed-off gun. The usual weapon for the new postnuclear world but very nice one.
You can find the Dr.James 12 Caliber left to the main door of Vault 101 outside next to the poor soul bones ( see screenshot).

Credits:
trent1542 for textures, sound and meshes of weapon
Bethesda Softworks for the wonderful game

Install.
1.Extract the files to a temporary location.
2.Examine the folder structure and make corrections
where necessary.
3.Copy files to (install folder)\Fallout\Data\
4.Start Fallout Launcher, click 'Data Files', place a checkmark
beside the .esp file(s).

Uninstall.
1.Start Fallout Launcher, click Data Files, uncheck
the .esp file(s).
2.Delete the files/folders associated with the mod.

Please let me know about the bugs)))
Enjoy!