Please pass on to your colleagues at Bushmaster a heartfelt "hooah" for a job well done on my M4A3 upper.
The fit and finish were impeccable, as was the fit with my old preban lower. The welding job on my Phantom was also flawless, and looks better than the birdcage ever did!
The best thing was receiving the upper a week ahead of schedule!
Going shooting over the weekend - I'll post a reply.
Again, thanks to Bushmaster