RE: Best "SIMPLE" rifle sling
I have had several slings through the years including the wide padded slings and a couple of "GI" leather hook and loop adjustables the best one so far is a hand fitted DIY 5/50 cord ranger sling . It fits my bolt rifle 2 shotguns and the Marlin carbine and fits me well enough to get the 3 point sling lock rest on the bolt an carbine .
I believe I saw it in F&S about 15 yrs ago .