Built this upper for those 600 yard shots during 3-gun matches. Turns out my current 16" does just as well but better for the house clearing stages. My "long game" just needs more rounds down range. This upper has the following parts. ODEN works 18" 1-8 Wylde 3-Gun profile barrel with rifle length gas system. ODEN works adjustable gas block. M-Lok rail. Smooth side upper with ambidextrous charging handle and M16 bolt carrier group. The compensator is from Lantac and works amazingly.