I got a Bear Creek 16" contour profile barrel for 6.5 Grendel. I mounted a YHM QD FH for my Ti Phantom and the groupings were around 5 MOA and all over the place. Without the suppressor on it grouped about 1.5 MOA. These were both 10 shot groups using Hornady 123 AMAX, factory loads.
I found that the shoulder area is .700 just before the threads. For suppressors and QD devices, I don't think there is enough shoulder. Both Silencerco and YHM both require a minimum of .720.
I don't know if for sure that is the issue or not. The can looks aligned, I see no shadows. Maybe the barrel doesn't like a can period, don't know. I like it, bought a complete upper, but now need a new plan for deer season since I won't be using this upper, at least the barrel, looking at a different barrel now to replace the BCA with.
Anyway, FYI.