Sacking to fix ballistic striker? (6,3)

I believe the answer is:

firing pin

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'ballistic striker?' is the definition.
'firing pin' can be an answer for 'striker?' (firing pin is a kind of striker). I'm unsure of the 'ballistic' bit.

'sacking to fix' is the wordplay.
'sacking' becomes 'firing' (synonyms).
'to fix' becomes 'pin' (to pin is to fix in place).
'firing'+'pin'='FIRING-PIN'

Can you help me to learn more?

(Other definitions for firing pin that I've seen before include "part of gun" , "used by gun" , "Mechanism detonating the cartridge in rifle" .)

I've seen this clue in the Sydney Morning Herald.

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