I own a Les Baer .308 sniper. it is, without a doubt, the most accurate rifle I've shot and that includes my custom 30-338. That being said - it weighs a lot - nearly 14 lbs with the scope. It is NOT a field rifle, although you can shoot precision tactical rifle competition with it.
The SCAR 17 is a field rifle. If you want a rifle that is accurate, but you can carry in the field all day - that would be the semi-auto rifle I would choose in .308. I've shot them and they work really well.