[Shooter 2.5]

I guess I can answer that.
There was nine yards of belted ammunition for each machine gun in fighter planes during World War Two.
The act of giving someone the "whole nine yards" was to unload everything you had at the person or thing.

[parsifal]

There is one I always wondered about:

Bread Pie at morning
Sailor take warning.

Does this have to do with eating hard tacky for breakfast means that the food supplies are running low? parsy.

[Rockpile]

I have also seen the phrase "the whole nine yards" referenced to WW I airplane ammo belts. The explanation is totally bogus.

If you have ever seen the 19th century poem about the English ships going to fight the Scottish freebooter--the one with the phrase "though I be wounded I am not slain, I'll lay me down and bleed awhile and then I'll rise and fight again"--well there is a statement in it about loading up nine yards of chain for the cannons.{To take down rigging I presume}. This poem was based, I think, on a much older song/poem from maybe the 1500s.

I'll see if I can find a link for this.