I have never really been sold on the idea of a scout rifle. As I recall, the Colonel specified this rifle to be light, chambered in a rifle cartridge such as 308 Win, detachable magazine, and forward mounted scope. Although I do not think he would have been necessarily opposed to a semi-auto in this configuration if it met the weight requirements, most of the time the scout rifle is thought of as a bolt action.
The weight requirement is more than a trivial challenge when developing a "scout rifle." Of course, an aspect of a scout rifle, under the Cooper consideration, is form - and most semiautomatic rifles are much more bulky than a bolt gun. So many of these have pistol grips protruding under the belly, a form factor far less sleek as a swept grip bolt rifle.
I like the idea of a scout rifle. It sounds cool. But what exactly is the scenario I would find myself in that I would not prefer to have either a regular hunting rifle, an AR with a red dot optic, or maybe even a handgun?
No handgun competes with a rifle for field use. As one who has prescribed to the use of specialty and sporting handguns for over 25yrs, it's an irrefutable fact no handgun will truly compete with a rifle for field use - in terms of speed to stabilize on target and delivery of precise killing shots.
Again, a bolt action will be lighter and less bulky than semiautos for portage and deployment.
A traditional, scope-over-receiver bolt gun can be just as fast to deploy on target as a Scout rifle. The major difference is the portion of the field obscured by the optic. Cooper wanted to be able to see more of the field, and only zoom in on the object which deserved a bullet - which is a worthy pursuit, however, in application, none of us really get into a gunfight with a bolt action, and even if that might be a part of our reality, we're generally not forced to do so with the same rifle we'd use to fill the stew pot.
Perhaps the scout concept, as a general purpose rifle, is a "jack of all trades, master of none" type weapon. Its cool, its neat, but not really a first choice for anything.
Scout rifles are neat and they are cool, but they've been proven wanting as a concept time and time again.
Is there any scenario you can think of where the scout rifle would be your first choice of weapon?
I'm prone to believe Cooper, in 2017, would favor a red dot, either non-magnified or only slightly so, on his scout rifles, as conceptually, they'd be a more relevant optic for his application.
Where this type of rifle can shine is shots on running game and rapidly engaging multiple targets at short to moderate ranges. As a hunter, there's really not much reason to shoot running game, certainly no reason to plan to do so on a regular basis, and a receiver mounted optic really doesn't hinder the ability to deliver these shots anyway - assuredly not hinder as much as a forward mounted optic hinders precision for non-running shots. If I'm snap shooting multiple targets, I'd rather be running an AR-10 so I can stay on the trigger and maintain contact with both hands to help stabilize the rifle better to engage targets more quickly and accurately.
I've done the scout thing a few times over the last couple decades, personally, I'm not impressed enough by the concept to stick with it.