I haven't used those but have used the ISOTunes sport advance. I'm not a fan. If you turn up the ambient gain too high there is a lot of static. Additionally I find that the plug works its way out of my ears when I'm cutting the grass. I also have the Etymotic Gunsport Pro plugs. I'd recommend those or the Otto NoizeBarrier rechargeable plugs.
Also I am not implying that all of them are a pos...quite the contrary. It might be a case of no one checking for that burr after they drill it. Poor quality control. Tell them you want a new slide and barrel.
Muzzle Brake, not Break...
My Spikes AR has a 14.5" barrel with a factory pinned Spikes Dynacomp brake, making the length 16" which is legal.
The upper you posted is a Colt upper and it has the Front Sight Post Gas Block, which does have a Bayonet lug. 95% of FSP gas blocks have them.