More than a barrel, or even a butt! (5)
I believe the answer is:
rifle
'butt' is the definition.
(rifle butt is a kind of butt)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rifle that I've seen before include "Root" , "Carbine" , "Flier (anag.)" , "Gun; plunder" , "strip bare?" .)