Someone here recommended http://supplycaptain.com as a source for paracord. I Just received a shipment from them of 7 x 100 foot hanks of 550 paracord in assorted colors.
The cord appears to meet the mil spec. The braided sheath is substantial and tough. Each of the 7 inner threads consists of two twisted bundles of fibers, as it should. The colors are vibrant.
The shipment was prompt and hassle-free in spite of its being international (From the US to Canada).
In my comment above I was not thinking of a three yarn vs two any other number in the individual threads, but rather of the 7 threads vs the undifferentiated mass of fine fiber I have seen making up the whole innards of some “paracords”.
EDIT. The Wikipedia article on parachute cord shows “commercial” paracord, which is how mine is described, and says its core is made up of seven two-ply yarns.
Still, even assuming the cord I received is not true mil spec, (supplycaptain says " our cord is modeled after US military issue 7 strand Kernmantle style 550 cord i") it seems to be of very good quality.
I have recomended Supply Captain in this website on previous occasions. Material I have ordered from them is prompt and accurate. I also order the reflective paracord from them. I have also contacted them about availability of more colors of reflective paracord, and they their feedback was prompt and friendly I will still reccomend them as a vendor.
I cannot discuss the definition of Mil Spec, or commercial. I know that what I am getting from Supply Captain is good stuff for what I am using it for.
I buy the paracord that’s labeled MIL-C-5040 Type III. It’s a couple bucks more, but it’s worth it because I don’t have to ask about it in an Internet thread.
I bought some paracord from White Moose Trading Co (whitemoosetradingco.com). Good price, beuatiful colors, nice feel, but it is kinda flat. Good if that is what you want, but I want/need stuff that will stay round when I want it to. :-\