The main problem is that most muzzle brakes and suppressors are 5/8x24 TPI and there are more to choose from.
Thread fit is the important thing with coarse or fine threads. the only time that it becomes important, is if the thread pitch causes infringement on barrel wall thickness. Then a fine thread is used to reduce the Minor Diameter of the thread, increasing the barrel wall thickness.
5/8 x 24 is the standard thread used most of the time and going to a coarse thread would only hinder your search for a Good brake or suppressor.
Larger brakes for big bores and barrels will/have larger barrel tenons and coarse threads because of size.
Probably no help, but an explanation why there is no advantage to an 5/8 x 18 thread over a 5/8 x 24 tpi.
J E CUSTOM
