I hear this question all the time and when I do I ask them what other items they are carrying with them. Everyone wants a 6 lb rifle that will reach out to 1/2 mile but then they pack around a 40 lbs of accessary gear!!!
Now do we need a good spotting scope, yes, do you need an 80mm Swaro for hicking around the hills, NO. I have heard time and again that you NEED a Swaro if you want to be able to see what your shooting at and tell what it is at long range. BUNK. I know I am going to **** off alot of guys out there but that opinion is untrue. I spent a week hunting mule deer in S. Dakota a week or so ago and the guide had an 80mm Swaro and I had my 66mm Cabelas that has had the hell beaten out of it for the past 7 years. Its even taken a few falls off the truck onto gravel roads, it certainly is time to replace the old girl.
That said, for some reason I was seeing things on that mule deer hunt that seemed to elude the guide with his $3500 scope. Even out to a couple miles, I could certainly see what I needed to see to determine if the buck we were looking at was work getting a better look at and my scope cost me $700!!! Not only that, it weighs about 40% less then the Swaro.
Now I understand that Coues are small deer and their antlers are usually pretty small so its smart to have good class but today, there are alot of options to get "GOOD" class in a MUCH lighter package then the Swaro. Such as the Leupold Mk4 tactical spotters.
I would much rather see a hunter give up a bit of spotting scope size and weight then skimping on rifle weight. Again, many will probably tell me I am crazy for these comments but a Swaro is not needed. Nice at time but certainly not a requirement for long range big game viewing.
Now to the rifle, you do not NEED 12 lbs for a rifle to shoot well at long range but its a simple fact that a lighter rifle requires a much better quality shooter for it to be accurately shot at long range. I have built several 6.5-7 lb class rifles that would easily take deer size game at 1/2 mile and even have a few customers that can shoot a light rifle well enough to be competent with such a light weapon but the vast majority of hunters out there, even long range hunters, myself included, need some rifle weight to dampen our bad effects on a rifles accuracy potential.
SO it would greatly depend on your shooting ability to determine how light of a rifle would work for you in the field.
From a rifle builders stand point, a light rifle will compromise in several areas to cut weight down. Those being barrel mass, which means that because the barrel is lighter in contour, it should be shorter to maintain proper barrel stiffness. A long light barrel is not a good combo for long range precision, especially with a high intensity chambering.
Also, stocks need to be light weight, which always to some degree effects a stocks stiffness and strength and flexability, all of these things can result in reduced accuracy potential.
In my opinion, a rifle needs to have a minimum of 9 lbs of bare rifle weight to offer plenty of barrel mass and plenty of stock strength. Put on any of the more popular LR hunting scopes and mounting systems and your into the +11 lb range.
Just my experience and opinion.