In the course of setting up numerous rifles, I’ve found that the choice of sling can be a critical one-and one that should be complementary in a number of ways. A good sling can be an invaluable aid to accurate shooting in the field, but a bad one is nearly useless.
As far as appropriateness to the platform, a thick, stiff leather “cobra” style probably isn’t a good, or necessary, fit on a superlight rifle. By the same token a thin 1” nylon strap likely won’t feel all that great on a dangerous game rifle. My own rule of thumb is to use 1” slings on rifles weighing around 7 lbs. or less and 1¼” slings on those that are heavier. High-quality leather, such as those from Turner Sadlery for service or precision rifles, or nylon, such as those from The Wilderness, are hard to beat.
Other considerations are format-Ching sling style, Rhodesian sling style (check out Andy's Leather), military style or simple carry strap style-and fittings; HK-style snap hooks, mash hooks, push-buttons or conventional QD studs. All can affect a rifle build or the decision as to which sling to buy, particularly if the fittings are permanently attached. By the way, another great one to consider is Brownells Latigo sling-just do youself a favor and order the model with pre-installed swivels!