I think the shooting qualities of a custom depends largely on the specific builder. A also believe that there will be a difference between a Benchrest custom and a rifle intended for hunting or tactical shooting. I have buddies that shoot Benchrest customs that have chambers cut so close that they don't even resize brass and use the same batch of 100 brass for the life of the barrel. These rifles are .25 MOA and better. The best custom long range hunting rifles I have seen were guarenteed to shoot .5MOA but generally exceeded that spec. I have one that can shoot .25 or better pretty consistantly tested with 5 shots at 500 yards. When it doesn't it's me, not the rifle. It was designed and tested for a specific bullet style so I never tried it with others. The biggest difference with this rifle is that from the first shot to now, about 300 rounds later, it has held point of impact, clean, dirty, warm or cold. The builder did the barrel break in. Also, the rifle cleans up in much less time than my factory rigs. Of course the fit and finish is superb. Some buddies with custom rifles
have seen similiar performance, others have not. This rifle was a gift so it is likely I won't get another custom. Most my rifles are "do it yourself" factory or just rebarreled. I have done fine with these, some capable of producing .25-.5MOA, but can see a difference in overall shooting qualities with my custom.