It's of far more use than just toting your rifle on your shoulder.
Deer hunters can take a lesson from trained snipers--The Deliberate Sling is slower to acquire due to the slide loop on the shoulder, but it's the steadiest.
Most advertisements you see for rifle slings actually are for carrying straps, which are not the same thing. A carrying strap allows you to tote your rifle on your shoulder or across your back so that you don't have to bear its heavy weight in your arms. While it's very handy, a carrying strap may cause you to miss shots since you become lazy and have your rifle on your shoulder, rather than in your hands when you need it. A sling is designed to brace yourself for steadier, more accurate shooting. Like snipers, hunters can benefit from slings, not carrying straps.
While leather slings have been around longer and have more fans than newer nylon designs, either type works acceptably. All that really matters is that the sling has enough width and the right kinds of adjustments for serious shooting.
Whether nylon or leather, it should be 1 1/4-inch wide and dark enough to blend into your environment. Of course, you need 11⁄4-inch swivels to match, with the quick-release type being most suitable.
The competition-type leather slings tend to have better and more adjustable keepers and hooks, with perforations instead of just a sliding buckle as a stop. Although my purist friends will criticize me for admitting it, the nylon slings can be adjusted more easily.
HASTY AND DELIBERATE SLINGS
The Hasty Sling position is called such because it can be assumed rapidly. It will significantly improve your steadiness, but not as well as the Deliberate Sling, which I'll cover momentarily.
The Hasty Sling requires only that you slip your non-shooting arm through it once, then, up close to the forearm, slip just your hand through a second time. By flexing your bicep and pushing slightly with your hand, you can take out all the slack until you're in a very firm and stable position. I'd guess that a Hasty Sling position takes less than two seconds to assume but improves steadiness by 40 percent.
This short loop is the Very Hasty technique for stabilized shooting.
To take up a Deliberate Sling, you must first release the swivel at the butt, then form a loop large enough to slide your non-shooting arm into the loop just above your bicep and push down the keeper or buckle until it's snug around your arm. You'll have to experiment with this to learn the exact spot to achieve it, but the result should be that once this loop's in place and you insert your hand between the sling and forearm, your position will be rock-steady, with considerable leverage bracing the rifle in place. When used correctly, a Deliberate Sling position will improve steadiness by perhaps 60 percent. With practice, you can learn to assume a Deliberate Sling in about 15 to 20 seconds.
But I must note a need for caution. In bracing too hard, you could pull the stock against your barrel and even pull the barrel off zero. This is not as perverse as it sounds. The U.S. Army found that heavy pulling on the M16's front swivel caused point of impact to shift almost four inches at 100 yards. Part of this effect undoubtedly was due to the M16's lightweight design, but hefty pulling could affect other rifles, too.
If your rifle forearm has double swivel studs, you could use a third Very Hasty technique, as developed for Jeff Cooper's famous Scout Rifle. The developer, Carlos Widmann of Guatemala, installed a simple leather loop between the two forward swivels. Slip your arm through only once, like the Hasty, then take slack out with hand pressure. This technique's almost as steady as the Deliberate Sling, and it's even faster to assume than the Hasty, while due to the swivel locations, the stock's pulled down and away from the barrel with less likelihood of binding. The only significant drawback is that when not in use, it flops around and can get caught in foliage. Usually, a hunter should assume a supported firing position, rather than employ his sling, because it's faster to get into, easier to maintain for long periods, and quicker to displace from. There is probably too much emphasis on sling shooting due to the influence of competitive marksmen, who fire in many events in which their only support is a sling. You should always attempt to use a bipod or expedient support, but lacking this, you'll find your sling a good second choice for stability.
I must admit that a sling is also a means by which you can carry your rifle, but only for short periods if the situation demands, such as when you need your hands free to climb a steep hillside. About the silliest you could ever feel is to find your hands empty when there should be a gun there.
Editors Note: With slight modifications, this column was excerpted from the author's book, THE ULTIMATE SNIPER (Paladin Press, 1993; 303/443-7250).