Most commercially available paracord is manufactured without adherence to US military specifications—even cord purported to be "military grade" or "milspec" is often substandard. Fewer inner yarns, corners cut in the manufacturing process, and the use of lower quality raw materials are all in contravention of military specifications for 550 paracord, but labeling regulations in the civilian world are lax enough that almost any paracord can be sold as "military grade."
If you want to know that the 550 cord you're buying is actually made according to military specifications, you need to know what those specifications are. Here's a quick and handy guide I put together so you can do exactly that (and of course, you can always purchase true military grade 550 paracord here at SGTKNOTS.com).
Fiber, Yarn, and Sheath Requirements for Mil-Spec Type III "550" Paracord
First, it's important to note that the US military defines seven types of paracord, all essentially differentiated by their thickness/strength. What's often sold as 550 paracord most closely corresponds with miliary-defined Type III paracord, which contains 7-9 yarns in the inner cord, with each yarn spun from three individual fibers made from, "bright, high-tenacity, light-resistant and heat-resistant polyamide prepared from hexamethylenediamine and adipic acid or its derivatives," with a melting point of 244 degrees Celsius (471.2 F).
Inner core yarns also have to be "wet shrunk" at between 90 and 96 degrees Celsius, essentially steaming them into a more compact and stronger yarn before they are sheathed into paracord. Sleeve or sheath yarns are made from the same material, then wet shrunk at between 68 and 74 degrees Celsius prior to braiding. No bleaching agents can be used on any yarns at any time, as this can lower the integrity of the cord.
Military grade paracord is not subjected to any stretching during the manufacturing process, as this can cause micro-tears that weaken the cord.
Paracord Strength and Thickness: Reading Between the Lines of Military Specifications
There is no exact measurement for finished military grade Type III or 550 paracord, but given the material specifications and the 7-9 required inner strands, paracord that is built to military standards should measure close to 4mm in diameter. The direct relationship between the number of strands used in the inner core and the thickness of the finished paracord makes thickness a fairly reliable measure of strength, so long as the right materials and proper manufacturing procedures were used.
The "550" in "550 paracord" refers to the minimum breaking strength of the cord, which for Type III cord is 550 pounds. Obviously, measuring the thickness of the cord and counting inner strands is a much faster and easier way to estimate strength after checking the manufacturing specs.
The DoD's Dos and Dont's of Coloring Your Paracord
Color is the one area of the Defense Department's paracord specifications that SGT. KNOTS deviates from. Natural colors or approved camouflage shades are the only approved colors for true mil-spec paracord; keeping your cord hidden can be useful in some civilian situations but isn't usually as necessary, so I stock an array of paracord colors that would otherwise be military grade.
The important thing to note about color is that certain oils, pigments, and dyeing processes can weaken the paracord, and that would make a substantive change to the military specifications. Manufactured correctly, from the right materials, and dyed using safe pigments and processes, your mil-spec paracord should be up to any task you throw at it.