Not a big shot in the gunnery world (6)

I believe the answer is:

pellet

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'shot in the gunnery world' is the definition.
'pellet' can be an answer for 'shot' (synonyms). I'm not certain of the 'in the gunnery world' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for pellet that I've seen before include "Lightweight bullet" , "Small pill" , "A piece of shot from cartridge" , "Piece of shot for gun" , "Small rounded mass" .)

I've seen this clue in The Globe and Mail.

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