First off,
no sling, tactical or otherwise, will take
any of the weight off your arms in a standing low-ready, high-ready, or off-hand position; a shooting sling is most useful in a sitting or prone position, but in those positions you should be using bone-on-bone skeletal support to hold your rifle up rather than muscle tension, anyway. If shooting in the classic off-hand position, give yourself at least
some skeletal bracing by moving your support hand back to the magazine floorplate or trigger-guard, and allowing your supporting upper arm to rest against your rib-cage - but this isn't all that "tactical," and is seldom if ever used in any kind of CQB training.
In a CQB low-ready position, you start with the rifle aimed in at your target, and just allow the rifle to settle downwards until your supporting upper arm again rests against your rib-cage - this gets the gun out of your line-of-sight and pointed in a safe direction, while taking some weight off of your support-side shoulder muscles.
You will seldom if ever be required in training or in any realistic defensive scenario to keep your rifle aimed directly at your target, in a standing position, for an extended period of time - if you don't shoot within the first minute or so, you'll probably be going to a kneeling position(lower-profile & more stable), barricade position(supporting the rifle with the cover you're using) or back to low-ready(covering your target, scanning for other threats). The only thing that will help you keep your rifle aimed at your target for a longer period of time will be pumping iron(just use your rifle if you don't want to spring for a set of weights).
Now, as far as slings go:
- Two-point slings are what you see on rifles slung over a soldier's shoulder when he has to march several miles with it, or on most hunting rifles; it allows the weight of the rifle to hang on the shoulder somewhat comfortably for long periods. You can use USGI leather M1907 slings or web/nylon M1 slings for support in sitting or prone, or adjust the length of these slings so they can serve as "hasty slings" when shooting. Adapters are available to allow a two-point sling to be used to support the rifle when hung horizontally over the back of your neck and/or shoulder; this is not comfortable on a road-march, but allows the rifle to be instantly ready for use while standing at a guard post or road-block, or if about to clear a building.
- Three-point slings are attached to the fore and aft swivels of your rifle(or at least in the vicinity thereof), and incorporate a sliding buckle(totalling 3 attachment points) somewhere on the sling; these are meant exclusively for keeping the rifle at a horizontal waist-level carry while patrolling without a rucksack or standing a post, you would have to support the rifle with your hands/arms while road-marching with a 3-point sling. These slings also allow you to let the rifle hang on your torso or swing the rifle behind your leg while you transition to your handgun when your rifle runs dry, malfunctions, or breaks. Most 3-point slings make it difficult to move the buttstock to your support-side shoulder in the event you need to shoot from the left side of cover.
- Single-point slings attach to the rifle at the junction of the receiver and buttstock, and wrap bandolier-style around your torso; again, not a marching or hiking sling, but more a sling for patrolling and CQB. 1-point slings allow switching shoulders much more readily than 3-point slings, but require you to use your arms more to carry the rifle. You will need to install an adapter plate between your AR's lower and buttstock to use a single-point sling without possibly fouling your operating handle.
Most of the "high-speed, low-drag" guys seem to be going away from the 3-point slings as being too complicated to don, doff, and use, and towards the 1-point slings for simplicity, ease of use, and ambidexterity. I've used the Tactical Tailor sling(
www.tacticaltailor.com) in Tactical Response Inc.'s Basic and Advanced Fighting Rifle classes(
www.tacticalresponse.com) with good results.
To try the concept out, take a GI nylon sling and adjust it so that it forms a loop going over your support-side shoulder and under your strong-side arm; then secure this loop through the rear sling swivel of your rifle. This is known as a Krieg sling, and it does most of what a single-point sling can for little or no added cost.
