Such absolutes would be great to have. In the absence of such, we are left with common sense and probabilities.
You have reasoned the rifles must be 36" and shipped in wood. Others have reasoned the rifles were 40" and shipped in cardboard.
"Common sense and probabilities"...? So, no factual evidence, Yes?
I have not "reasoned" anything.
I am curious, how a cardboard box / crate court hold, at minimum, 550 lbs? (36" , 5.5lbs x 100) And how such a container would be moved? Certainly not by hand? On a large pallet? ( what's the old line , " 10lbs of sh#t in a 5lb sack")
Anecdotally - not factually - googling rifle containers for bulk shipments brings up .. a lot of wooden crates.
I will do more research.
Anecdota