No big shot in the gunnery world (6)

I believe the answer is:

pellet

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'no big shot' is the definition.
'pellet' can be an answer for 'shot' (I've seen this before). I am not certain of the 'no big' bit.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for pellet that I've seen before include "Lightweight bullet" , "Small ball of shot" , "bit of shot" , "Piece of shot as for shotgun" , "Small ball of iron" .)

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

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