Rechambered to a match chamber. Nemo does this machine work on the side but has a pretty good following on RFC. Basically, he cuts off about 1/4" from the chamber side and re-reams the chamber for a tighter fit and then re-crowns the muzzle end.

It's supposed to rival the aftermarket barrels for accuracy and only costs about $85. You can also add in other things like hand lapping and moly treatment.

The downside, as with all match chambered barrels, is that extracting an unfired round may or may not work anymore. Usually, "tuning" the extractor or buying aftermarket remedies this but there's no guarantee.