All About Pocket Knives

My son brought me this over the weekend. I did a search and found several examples, but not an answer to my question.
What significant difference (if any) is there between the ones marked Imperial and the ones marked MILPAR COL. This one's marked with the later.
It was sealed in the original 1969 (marked) packaging. Kind of surprised they weren't packed in cosmoline.
Thanks

WB

Here's what little I know about these. During the 1960's, the army purchased about 1.6 million of the M6 bayonets for the M14 rifle. The majority was made by Imperial. Columbus Milpar & Manufacturing made somewhere between 360,000 to 400,000 of them. Here's a link to a government document in which Camillus was complaining about the fact that Columbus Milpar got the contract.
http://www.gao.gov/products/454797#mt=e-report

And here is a link to a patent MILPAR filed in 1965 relating to the manufacturing process they used to make bayonets.
http://www.freepatentsonline.com/3218892.pdf

Thanks Blue, that was very helpful.

WB

Nice one Jerry and congrats!!

WB

Now if I just had the M-14 to go with it.