Weapons that are comfortable when recoiling (4)
I believe the answer is:
guns
'weapons' is the definition.
(gun is a kind of weapon)
'are comfortable when recoiling' is the wordplay.
'are comfortable' becomes 'snug' (similar in meaning).
'when recoiling' says the letters should be written backwards.
'snug' reversed gives 'GUNS'.
'that' acts as a link.
(Other definitions for guns that I've seen before include "Snug weapons?" , "Firearms" , "Bangers" , "Transportable armaments" .)