I am about to click the button to purchase an Aero Precision M4E1 20" Wylde 223 SS fluted bbl complete upper. I will also purchase their BCG. My question is will that upper "run" with their M4E1 lower with rifle buffer and spring and Magpul MOE rifle stock??? The upper has a rifle length gas system. I thought matching rifle length gas system with rifle length gas system. However I am a newbie with AR15 builds.