To BCM's credit, they seem willing to consider that I'm not just a crappy shooter... I just received this email from them:
Thank you for the update and the pictures, it really helps to illustrate your description of what you are experiencing
The following is a guide to "break-in" based on our experience. This is not a hard and fast rule, only a guide. Some barrel, chamber, bullet, primer, powder, pressure, velocity etc. combinations may require more cycles some less. It is a good idea to just observe what the barrel is telling you with its fouling pattern and the patches. But once it is broken in, there is no need to continue breaking it in.
Initially you should perform the shoot-one-shot-and-clean cycle for five shots. If fouling hasn't reduced, fire five more cycles and so on until fouling begins to drop off. At that point shoot three shots before cleaning and observe. If fouling is reduced, fire five shots before cleaning. Do not be alarmed if your seating depth gets longer during break in. This is typical of the “high” spots in the throat being knocked down during this procedure. It is not uncommon for throat length to grow .005”-.030” from a fresh unfired chamber during break in.
Stainless
5-10 one-shot cycles
1 three-shot cycle
1 five-shot cycle
If after your break-in period you still have accuracy issues, please let us know and we would be happy to take a look at your upper.