^^^I don't really agree with the above statement^^^
When building a custom rifle you get to choose all the parts that go into it. You choose to action, and what configuration. Lots to choose from in this, right bolt, right port. Right bolt, left port. Left bolt, right port ect. Single shot action, mag feed action.
Barrels, calibre, chamber, twist, length, profile, fluting, straight taper, Palma profile, the list goes on and on.
Traditional stock, prone stock, F-Class stock, hunting stock, chassis?
Triggers, lots to choose from, even with a TT you have the choice of a flat shoe, curved shoe, and set up for different weights, with or without safety,with or without bolt release.
By choosing different parts to build your custom rifle you are building a unique rifle to your specs, rearly will you find another one exactly the same.
The one problem building a custom rifle is that you are building it to your specs. And when it comes time that you want to move it along, you will never get the price that you put into it.