Accuracy is the result of a complete system, with the barrel itself being #1 on the list IMO.
Chambering job comes next, receiver work (receiver and boltfaces, lugs) followed by stock/chassis fitment (bedding job), trigger, handload development, etc.

That said, Bartlein doesn't sell off-the-shelf prefits as do some others. If you're capable of shooting the cost difference (and don't mind the price tag), most concur that cut-rifled barrels are the top tier- Krieger, Proof Research.

Just screwing a $600 barrel into a receiver isn't going to guarantee optimal results at the target.