I will walk through the steps I use to fit a Holland brake.
1. Determine the diameter of the barrel where the brake shoulder will bare.
2. Take this diameter and with a set of calipers transpose a line at this diameter on the tapered shank of the brake. Then take a rough measurement from this transposed line to the location where the muzzle will be at the beginning of the first port. (This is a very rough measurement, we just want to get an idea here of how long the threaded portion of the muzzle will need to be)
3. I generally add 0.050" to this rough measurement to make sure I have more threaded length then I need. Will explain this more later.
4. Cut the barrel muzzle to dimension and thread it to fit with a high quality class 3 thread fit. On a side note I have seen many brakes that are fitted with a class 2 thread fit work loose when fired. With a quality class three fit you can put a break on by hand just until the brake and barrel shoulders bare and it will now unscrew when fired. Thread fit is very important in my opinion for keeping a brake where it should be, tight on the muzzle!
5. Once the muzzle is threaded and has a proper fit with the brake, It is now time to cut the tapered section of the brake back until its diameter matches up with that of the barrel diameter. This takes a bit of time to do but if you are careful you can generally get the brake to index perfectly as it comes into matching diameter with the barrel diameter.
6. Sometimes however this does not happen. Just simply will not meet up correctly so you cut the brake back until its diameter matches or is very slightly larger then that of the barrel.
7. Then the barrel is placed back in the lathe and the barrel shoulder is set back very slightly until the brake indexes perfectly vertical. IF we simply set the brake back more, the steep taper on the brake would result in a poor matching fit. Since the barrel is tapered to a dramatically smaller degree the increase in barrel diameter is generally not enough to be concerned about.
8. Once the brake is fitted and indexed properly so that the diameter of the brake and barrel match up properly you would notice that the muzzle extends into the first port of the brake to far. This is by design.
9. The muzzle is now crowned with the proper live piloted 11 degree crown cutter until muzzle is set back to perfectly match the beginning of the first port on the brake.
There is certainly more time involved in fitting a Holland brake or any other brake that needs to be indexed but it is not dramatically more. They are more difficult then just threading a barrel and screwing on a vias type brake.
This is what we are after, a properly indexed brake with proper fit.