Welcome to the Hide Barker. Interesting choices, and I say that because while the SCAR 17s is fairly accurate, they're not necessarily a long range gun. The reason is with a 16" semi auto, you're really not going to be able to push the .308 fast enough to stay out of the transonic region all the way to 1k, and definitely not beyond. Since you're new to LR shooting, when you hit the transonic region is when the rounds begin destabilizing and your accuracy goes to shit. Maybe with some good 155gr Scenar rounds with a high density altitude could, but certainly not with the heavies. Where are you and what altitudes will you be commonly shooting at? I'm not criticizing, just being realistic what the barrel limitations bring. Now if you're ever able to come up with the 20" barrel (still vaporware at this time) you might have a different story, but not until then.
The SCAR is a lightweight "battle rifle" and it performs very well in that accord. I think you might be better off dialing back the long range expectations and keep it medium range. Like 800yds and in. What that means is you can look at some different mid range optics that will save you money (to buy more ammo), and will also give you the opportunity to go with a lighter optic that is still a top performer and can dial down more on the bottom end to open up your field of view when shooting close range.
Starting off, I would be looking at the Nightforce F1 3-15x. Weight with mount would be running in the 2 1/2 lb region and would get you all the way out to 1k still when you want to shoot the long distances. The Leupold Mark 6 3-18x is another ideal optic for that rifle saving you even more weight. Both still Made in America to boot, durable and backed by great companies. I would recommend the Vortex Razor II 3-18, but 3 1/2 lbs+ of of optic/mount on top of a 8 lb rifle can be awkward and unbalanced. Your choice there.
Magnification doesn't get you out to the long ranges, turret travel does and all the optics I suggested would get a .308 out to 1k even without a canted base (would still run a 20moa though). Magnification only allows you to resolve and identify the target easier, but most of us are staying under 20x even when pushing the long distances. The hotter it is out, the more you get the mirage effect that is amplified at high magnification. The sweet spot on many days is around 18x, some even less.
As for the suppressed shooting, just check it when you mount it up to ensure it's centered or you run the risk of a baffle strike. If at anytime you see your rounds striking the paper sideways (known as "key-holing"), immediately stop shooting because you're getting baffle strikes for sure. As for accuracy, every system is different. Look for a shift in POA/POI when changing from suppressed to unsuppressed, and it will like some types of ammo and hate others. That's where reloading comes into play for squeezing the real accuracy out of it.
