Rather apt unloaded firearm (1,6)

'rather apt unloaded firearm' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?

'apt unloaded firearm' is the wordplay.
'unloaded' suggests removing the centre (the content of the word is unloaded).
'firearm' becomes 'rifle' (rifle is a kind of firearm).
'apt' with its centre removed is 'at'.
'at'+'rifle'='A TRIFLE'

Can you help me to learn more?