the whole nine yards

[ZenBeam]

Yeah, this comes up often, and this ammo belt length “explanation” shows up a lot. Here’s the most recent, from December. Post 4 there gives links to a bunch of previous threads. I’ll just quote it here for convenience.

@Saltire

I was going to try to post links to all the threads we’ve had about this in the past, but it’s a bit daunting. This is, shall we say, one of the Great Questions of the SDMB.

Instead, I’ll just give you the most recent 5 threads. The fifth one has an excellent set of links in the second post to many more discussions here.

The Whole Nine Yards - from Vietnam?? - Cecil's Columns/Staff Reports - Straight Dope Message Board

did the whole nine yards issue ever get resolved - Cecil's Columns/Staff Reports - Straight Dope Message Board

Whole nine yards (again) - Cecil's Columns/Staff Reports - Straight Dope Message Board

The Whole Nine Yards - Cecil's Columns/Staff Reports - Straight Dope Message Board

The whole TEN yards! - Cecil's Columns/Staff Reports - Straight Dope Message Board

As of now, I believe the earliest reference in print of this phrase is the one discovered by our own samclem, which is referenced in the OP of the third link above. It is from 1964, which makes the kilt theory implausible.

Sam’s discovery includes not just the phrase in print, but a definition. It is stated to be space-program slang for a line-by-line report on a project.