OK, so here's the story.  I have been shooting all of my life, but I never have learned how to correclty use the military sling for off hand shooting.  Where can I get the scoop on use and adjustments?

Join the Army (if they still teach long range marksmanship...the Marines do for sure), or attend a match.  

There are enough people at most matches who are not shooting to help you get set up, and I have never met shooters unwilling to share what they know.  

You will need:  a shooting coat, shooting gloves, a sling, comfortable boots, and a mat.  A rifle too.  All these pieces of gear work together to help you form a stable platform.

Check the library too.  Ther may be some old marksmanship books there that the librarians have not thrown out as being too violent.

The downtown bookstores may have books too.

At one time, up through the sixties, most high-schools had varsity shooting teams and ranges below the gym.  Times have sure changed.

Join the NRA!

Try looking down the page in the [url=ar15.com/forums/topic.html?b=3&f=19]Slings and other accessories[/url] forum.

If you go to the Fulton Armory website, I believe they have a FAQ explaining the use of the sling.

www.nationalmatch.us

(As you can see, AR15.com is for photos and gossip, not shooting)

It's my understanding that the military sling is most useful in the supported positions, like the prone, and is pretty much useless in offhand and unsupported firing positions.  

Check out Col. Cooper's book Art of the Rifle for information on rifle shooting positions. The Fulton-Armory website has good instructions on the use and adjustments of the military sling.