Rifle slings have come a long way since the days of the carrying straps. So, here are some simple rules to follow on sling usage. Most slings can be broken down into either a single point, double point or triple point. Triple points have gone the way of the dinosaurs for the most part, which leaves the single and double point. For most applications a good adjustable double point sling will get the job done.
First, the sling should not interfere with the shooter’s ability to get accurate hits. If the sling gets in the way or prevents a consistent mount then modify it or upgrade to a better sling. Next, your sling should allow you to obtain all three of the ready positions; high ready, low ready and tuck/close contact. You want to ensure that you can work from all three of these ready positions without being jammed up because of the sling. Being able to assume the three most popular shooting positions, standing, kneeling and prone along with the more unconventional shooting positions is also a must. Reacting to contact and quickly moving into these positions to achieve a first round lethal strike should not be hindered because of your sling. Moving the weapon from your strong side to the weak side is also something your sling should not interfere with and while this has a lot to do with how snug you run your sling it also is a by product of some slings. Lastly, the sling should allow safe and secure stowing of the rifle when you go hands on and without having to cinch it up.
Once you figure out where the sling falls in with regards to gunfighting, you next look at how to attach the sling. There are generally four attachment points on a rifle; the front sight A-post, the delta ring, the end plate and the buttstock. While not every rifle has all of these attachment points, they still exist. I have found that the best all around attachment point configuration is the delta ring and buttstock. This gives you a “fatter” sling circumference without fully extending the sling making it more useful when wearing armor or chest rigs. The front sight and buttstock give you the “skinniest” sling circumference, which is too tight for most. I found the delta ring and end plate are just a really crappy single point sling and should be avoided. Which leaves the front sigh post and the end plate, this produces a top heavy sling configuration. When going hands free you ideally want the muzzle to drop straight down, the delta ring and buttstock accomplishes this task the best.
If you run the slipperier nylon slings make sure you do something with the bitter ends. You can either tape them or dead man them or even both. I find that dead manning the bitter end ensures the sling cannot slip through allowing the rifle to fall free and bounce off the deck. You can double the tri-glide buckles, but better is the dead man.
You still need to define your mission when selecting a sling, but the sling should never interfere with your ability to fight.