I don't know pee from paint or @#$%/!! from puddy, but I have an opinion. Listen up Mike.
A custom gun is built from a blank, though a pre-carve may fill the bill to keep the cost lower. There is an agreement between a builder and a client from the get-go as to what the rifle will be, and this includes allowing the builder free reign. A GOOD custom gun is produced when the customer does not insist on this piece of hardware, or that, which almost always is wrong for the piece being made. A nice rifle hanging for sale on the wall in Dixon's store, or on TOW's web site, though it may have been custom made, is not custom made for a new owner. A custom gun is made by commission for an individual. Again, you could buy a custom rifle made for someone else, but it is not a custom rifle for you.
Just my opinion and philosophy. I stand to be corrected, or at least you could try!