"Long range" sorta varies with the shooter. Generally, a "good, stiff breeze" will move a .223 bullet about six inches at 300 yards.
My Ruger light sporter in .223 is a half-MOA critter. I've had no trouble with prairie dogs to 300. (Ample enough numbers that there was no need to look further.) It's not too heavy to use as a walking-around rifle. And I'll admit I look with favor on weights below eight pounds.
Heavy barrels make sense for long and fairly rapid strings of shots. They are no more precise than a light barrel for the first two or three shots, so the usefulness varies with what's intended.