ar15 gas block
hey so i have a DoubleStar StarCAR heavy barrel 16" carbine. I was wondering what gas block i could replace the a-frame front sight with. i want a low gas block with rails, or just a gas block without rails, but no front sight. suggestion? I don't know what diameter i need either. is it .937" .750" or .625" ? also, I need to know how to install it once i get it. or how much i should expect to be charged for installation by a gunsmith?