300 blackout pistol build - Aero Precision M4E1 Threaded 10in .300 Blackout Complete Upper Receiver with Flash Hider

Purchased this upper for my 300 Blackout pistol build and received it within 10 days of ordering (great free shipping by Optics Planet as ususal!). I haven't completed the build yet, but this is my second Aero purchase (first one was a 556 build) and am very impressed with the new Atlas R-1 handguard, as it's smaller than their previous handguard and feels much better in my hand, as well as shaving some weight off the finished gun. I'm looking forward to running this gun fully suppressed with subsonic ammo.