I paired a Bravo Company upper with a Stag Arms lower and they worked together perfectly on my build earlier this year. I bought all milspec parts from the above two companies as well as Daniel Defense and Magpul and didn't run into any issues. Mine is the top all black AR. The other is my son's. We built them together. Fun project.
“Once you have had a wonderful dog, a life without one, is a life diminished.” - Dean Koontz
STI Eagle (2), STI Trojan (2), STI Edge, STI Guardian, STI Sentinel, STI VIP, STI Ranger, STI Tactical 4.0, STI Rogue, STI Escort, 1943 Remington Rand 1911A1