The answer is to build your own AR and then you'll know what went into it. I built mine on our dining room table in a couple of hours from scratch. It runs flawlessly. Lastly, any AR out there these days should stabilize anything 62 gr and under as it is hard to find one with anything slower than a 1/9 twist rate. If you're running something north of 69 gr you'll be wanting a barrel with a 1/7 twist.