I ask this of those who have military experience cause you maybe know what I would need better than anyone else. I do a lot of hiking here in the mountains of NW Montana. Always carry a M4 just in case. Question is regarding the best sling for comfort and access if needed in a hurry? When hiking 9-10 miles on average in steep terrain, you tend to want to get rid of the pack, the gun, and anything else to make it easier on the way back. What would you suggest since I assume you have done your share of carrying a weapon for long periods of time? What I have tried so far is not the trick. Just need some input on your suggestions for a sling to try. Thanks

I used a cut down M60 sling, but I am sure there are better ones out there on the market.

Hiking as in Day Hiking or Backpacking?

Day hiking - one of the patrol type slings.  I would figure out a eay to transfer most of the weight to your shoulder straps.

Backpacking - I done a little thinking about both pistols and the black rifle.  Pistol in a sternum holster fastened to the left shoulder strap and cross strap.  Keeps it off the belt and out of the way of the "belly band" but quickly available.  This on an internal frame pack.  On an external frame pack, the holster has it butt forward over the left shoulder between the pack and tent/other rolled items.  This keeps it pretty much concealed but available for quick draw.  Rifle mounted vertically on the right side of the pack such that you can bring your right hand up to the grip and pull forward and down to a ready position, likewise the left hand could come across and grasp the fore and pull forward.  the butt in a "bucket" and the foreend secured by a strap that is releasable by the hands when grasping.  You could evn set it up that yu use both hands to draw, right hand up to grab grip and hold while left hand crosses, releases fore-end strap and grasps fore-end.  Ready to go.  would take some personalized work to fit to   you and your pack.  If you are carrying fishing rods that extend a bit you could move the rifle up a bit, if not, lower and a left hand grab only.  

These assume you can spare a few more moments than a soldier on patrol in a hostile area.  If you don't expect the few moments will be available use the patrol sling.  (What are you doing there??)  Putting the rifle available on the pack keeps your hands free.

Kifaru has somethinng called the "gun bearer" or something along those lines. Check their website. I haven't found a sling that is going to be comfortable for any extended period of time, but this thing seems to have potential.

http://www.kifaru.net/MGgunber.htm

A nne to ten mil hike is an awful long time to have "the rifle at ready" position.  Can't remeber ever having to go that long without some ideas of when to have "rifle at ready".  Over that long a period of time, you'd want to get that weight off of your neck, or , unless you've got tremendous, stamina, and wind, that will kill your energy.  
I'd think attaching the butt to whichever shoulder strap you shoot from, and allowing the muzzle end to move freely might take care of that.  Your weapon, nw is one w/ your pack/ruck.  A QR buckle/snap/carabiner would help sparating yourself though.
The PIA, thouhg is that on those steeps, your goig to have that muzzle down at your feet, slamming rocks, and possibly tripping you up.
With that rifle not in your hands, and integral to your ruck, you risk a fall and the inability to protect your weapon.  
Luck, SUL2

I've roadmarched with an M-16 a time or two.  Nowadays I use a sling from CQB Solutions although I don't roadmarch anymore this sling would be damn useful.  cqbsolutions.com

Thanks for the replies.

I do alot of hiking myself and also a 15 year Army veteran. I use the standard issue sling, but remove the "slider" and replace it with a standard buckle. I prefer carrying the weapon across my back for long hikes, and the slider tends to dig into your back.

I use a Tactical Tailor sling.  Seems fine for tactical movement and is great for slinging the weapon out of the way for when you dont need the rifle at the ready position like when your in the chow line or doing maint on the BFVs.