A dedicated long range rifle has a couple of drawbacks. On of them is weight and the other is length. Carrying a 15-16 pound rifle with a 32 -36 inch barrel is a chore and having it ready to use is even more difficult. The benefits of the steadiness of the extra weight and the additional velocity from the extra barrel length come with disadvantages which are more than a lot of people are willing to endure; however, some of us stubborn souls persevere.
The new stretchy, padded, wider slings are a big relief to the older narrow sling and ease up a lot of the “bite” on your shoulder. Nonetheless the gun is still heavy and long. When you have a back pack or you are going through heavy brush it is often desirable to carry the gun some way other than the traditional one shoulder method. It is also good to be able to switch positions to give hurting muscles a rest. Also, if you think you may want to take a shot at an animal at close range then the gun must be “ready” and “stable”. If you have shot an animal and are not positive it is dead and must go into the brush then your gun must be ready. The process of checking out the animal may take as much as an hour in steep mountainous terrain to get from one mountain side to the other so you will be worn out when you get there and carrying the rifle at port arms while climbing up a hillside may not be feasible.
To accommodate the long heavy rifles, I have taken additional straps and added them to each end of some of my favorite slings. The additional length can be shortened up to a conventional length for the traditional one shoulder carry or it can be lengthened out to carry over the opposite shoulder with the gun riding on your back. My favorite style is with the sling lengthened out and placed over the opposite shoulder and the gun riding parallel to the ground with the muzzle forward. In this position you guide the gun with one hand through the brush and trees and if you need to the gun will come up to your shoulder for an offhand standing or kneeling shot and the sling will assist a little in stabilizing the gun. The other position I like is the sling over the opposite shoulder and the gun riding diagonally in front with the butt at the right hip and the barrel forward and to the left, but it will not allow for the gun to be shouldered with the sling set this way.
In order to insure that the padded part of the sling rides correctly you must have adjustment at both ends of the sling. Attaching additional straps to a sling depends on the original sling design and your own ingenuity. I would not advise using your wife’s sewing machine for working on the straps but most likely a baggage/shoe repair shop will do your sewing for only a few bucks. A camping gear store will have webbing and buckles.
Here are a couple of guns with modified slings next to a Remington 700 SA and a conventional sling.