I have the Ruger Predator rifle in 308 very similar to the 300 Blackout, has a short 18 inch threaded barrel http://www.ruger.com/products/americanRiflePredator/specSheets/6974.html and shoots real well, with a nice trigger. If looking for a shorter barrel 308 it fits the bill for me. I don't think you can go wrong with any of the ruger rifles. As for the blackout, I also think you would be better off with the 308 for what you want to do, it will shoot greater distance and the ammo is a lot easier to find. I enjoy the 300 blackout for close range shooting and think it is a great pig caliber (but if I didn't reload I wouldn't have a blackout), but for deer at a distance and paper punching and tannerite shooting I would go with the 308.
And that is what I think my focus has shifted to. Although I think the stock is hideous. I'm also considering the always popular remington 700 sps in 308 as well. I feel it is worth the few extra bucks.