Great upper receiver! Fits perfectly with the Aero Precision Thunder Ranch M4E1 lower I ordered from them too. This is my 2nd Thunder Ranch AR and countless Aero builder sets. Upper weighs 6.5 ounces. Not one scratch. I wanted an upper without forward assist. Q: If a bullet doesn't feed, WHY JAM IT IN? No more forward assists for me please. Much faster to tap n rack. No one ever practices with a forward assist anyway so why expect you'll ever use it in a hot situation, be it real or competition?