I have two - a 270 wsm and a 22-250
They both shoot like the others here have stated. My hunting partner has a 270 win and it shoots just as good.
I did a fair amount of reading on them before buying my first and just about everyone says the same thing, GOOD SHOOTERS.
Don't know about building from the action. Unless you want something they don't make and unless you need to shoot less than .5 MOA just spend the $500 or so and get your self a great shooter.
BTW that new Barns tipped bullet shoots very good behind R19 in my WSM.
Rick Nolan, SPHR