Spetznatz Ballistic Knife was aluminum w/a Steel blade hollow aluminum tube behind the blade inside was a Shock absorber spring & you compressed it into a handle that had a catch & was secured with a pin like a granade It would shoot into a hollow core door from 10' with no problem stick in the length of the blade & you are right SOF sold them in an ad back in the early eighties
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it did not use a propelant or cartridge to expell the blade