For a 16" rifle what is your favorite barrel profile and why? Seems like the vast majority are M4 profile, and then you have your HBAR which looks to me like the same diameter as the M4 just without the cutout, and then the pencil or lightweight. Beyond looks and the rarely used option of actually using the m4 cutout to attach something, what is the advantage of this profile? I've had someone tell me that the cutout is positioned at a harmonic balancing point so that it doesn't affect barrel accuracy, but I'm calling BS, I think it's where it is because that's where it needs to be to attach an M203. Not saying it affects accuracy that much if at all over an HBAR, but other than being a tiny bit lighter, why would I want one? I'm seriously considering a lightweight profile. Those that have shot lightweight/pencil barrels on ARs, how much stringing do you experience with warming?