C products makes good mags in about any caliber you could want. I've found the A4 uppers to look weird with a standard front sight sticking up there when you've got a scope mounted and no rear sight. You can get many scope mounts for the A2, and then you still have usable backup sights and a carry handle.
Blackthorne is the most affordable, and while it won't have the finish of a Colt, it'll still make a great brush gun you can be proud of.
I'd avoid chrome bolts and bores unless you've got a pile of old corrosive ammo AND you hate to clean, to me its more money for no improvement.
1:9 is probably all you'll find for the 7.62, and that should stabilize up to at least a 180gr projectile, but then you're handloading, which can be very good. The .223 will probably have a 1:7 or 1:9, and they will both stabilize the heavier (70gr +) bullets well, but thats still light for bear (and many deer too). You might have better luck (if terminal performance is more important than ultimate accuracy) by going with the early 1:12, the first ones given to the military were getting reports of tearing combatants in half and spilling innards everywhere, till the rate was tightened. Now you can hit the guy at 200 yards all day, which is good cause he won't stop till you get a head shot. Maybe you should consider the 6.8 Remington. Maybe different uppers?
AR's are great, you'll love yours!!
