The web sling has been phased out of USMC use.
I was looking around, and I couldn’t find a single set of instructions on how to set up a Parade Sling. Mind you, a Parade Sling is not a useful marksmanship tool like the loop sling, but when pressed you can still use it as a hasty sling. The purpose of the Parade Sling is just for close order drill. It has been used on the M1 Garand, M14, and the various M16 family of service rifles.
To set up a Parade Sling you will need a Web Sling.
The green web sling has a M buckle (or “sling slider) sown into one end and a metal crimped on tip on the other. Often these tips will come off over time. You will also need the J hook and sling keeper. The sling keeper is sometimes called a “sling compression fitting”.
These slings have come in multiple lengths and materials. From cotton to nylon. I have seen black aftermarket ones that function fine, but have sub-par stitching.
Slide on the J hook with the J facing the M buckle. The stitched end of the webbing should be on the opposite side as the J hook.
Run the webbing back though the M buckle. The stitched end stays inside.
The distance between the M buckle and the J hook is up to some debate. I remember it being the width of 4 fingers. But I have heard of units using the length of the long side of an ID card, or 4 inches, etc.
Slide the keeper on with the opening side on the same side of the sling as the opening on the J hook.
Clip the J hook onto the buttstock end of your rifle, run the sling though the front sling swivel and back into the keeper.
When properly set up, the J hook and the sling keeper should open to the inside (rifle side) of the sling with the M buckle on the outside.
Often you will see the Parade Sling shown as tight up against a magazine or the pistol grip. On the AR15 this is wrong.
(26) Parade sling.USMC MCRD Parris Island: Drill Manual
The rifle will have a parade sling for all movements except for Stack Arms and Sling Arms. The rifle sling will be as tight as possible on the left hand side of the pistol grip near the selector. The upper sling keeper will be positioned so the sling does not dangle.
The correct way to have a Parade Sling on the M16/AR15 is to have it on the left side, as tight as possible. Running the keeper back toward the buttstock to prevent a dangling loose end.
Longer versions of this sling may be too long to properly set up a Parade Sling on a M4.
If you are using a shorter version of this web sling, the keeper may end up over the mag well or hand guard. Some keepers are tighter than others, and can be hard to close. While I was in, I would push the keeper against the rifle to close it. It was the quickest and easiest way to do it, but it would scratch the rifle.
The Parade Sling home is on the drill field.