Timing is next. The first photo is where the brake started. I view the brake and barrel as a clock face. The black line on the barrel is top dead center. The line is at 12:00. The brake is at 10:30. I divide one by the thread pitch. In this case, twenty eight threads per inch. This gives me .0357 per revolution. I divide this by twelve to get my clock face (.0029 per twelfth). I now multiply by 1.5 to get the brake to top dead center. I take .0044 off the barrel shoulder. In practice, I would take .003, test fit, and approach the final cut carefully. The brake has been timed in the second photo.
I check my dial in before cutting the crown. This crown has two steps. The main cut is eleven degrees. The second cut is a tiny forty five degree chamfer. All cuts are made from the center out to avoid pushing a burr into the bore. The tiny chamfer breaks the sharp edge so the crown doesn't wear quickly, and provides a very visible indication the crown is perfectly concentric to the bore.
The brake is now bored to the correct size, and chamfered. I start with a centering drill, finish with a drill bit or chucking reamer. I cut the brake bore .020 over bullet diameter. Clearance and alignment is checked with the indicator rod.