Barrel and stock of gun (4)
I believe the answer is:
butt
This clue is a triple definition!
'barrel' is the first definition.
(I know that butt is a type of barrel)
'and' is a link.
'stock' is the second definition.
(butt is a kind of stock)
'of' is a link.
'gun' is the third definition.
(thesaurus)
(Other definitions for butt that I've seen before include "What goat may do" , "End of stock" , "Bottom end of a rifle" , "Blunt end - target of ridicule - hit with the head - cask - US backside" , "Fag-end" .)