I have really loved the older Uncle Mike's Military Slings. Uncle Mike's stuff is somehow connected to Butler Creek now and I've been told the leather SUCKS. Natchez has one by Boyts on sale right now for $20 and they're quality.
The other one that I have yet to use but that gets really high marks from people I've talked with is Brownell's Latigo sling. I just added a lovely little Mexican small ring in 7x57 to my gun cabinet and she screams for one of these. I'm going to spoil her with it and I'll let you know how it works out... how she likes it, if you will
When in the field for LRH, do y'all use a sling AND a bipod? I read Col. Whelen's book and he suggests using a sling in prone, but I'm curious whether y'all use one w/ bipod?