For sale, 20" musket A1 profile barrel complete upper receiver group. This was professionally assembled by Retro Arms Works around Jan. '24. All the parts are quality milspec ordered from Brownells and consists of Brownell's and Colt parts. The upper receiver was NOS surplus M16A4 w/M16 rifle feed ramps (not M4 feed ramps) from Sherluk. The barrel is 20" M16A1 pencil profile 1/7 twist w/M16 rifle feed ramps from Green Mountain. The BCG, A2 handguards, and carry handle sight are all Colt, and the rest of the parts are Brownells. Carry handle sight was zeroed using R.I.B.Z. My accuracy with iron sights @100y was around 3-4 MOA shooting prone. Round count is roughly 500, never been used as a pry bar. Asking for $580 cash for complete upper. Let me know if you have any questions.