Finished drop-in barrel will match the factory contour and is ready to be installed into the factory stock. Precision reamed, button rifled and air gauged to +/- .0005" to provide the competitive accuracy and constancy that has made Shilen famous. Shilen barrels have probably set more world records than any other barrel made, because so many shooters rely on them. Requires a Barrel Nut Wrench and Caliber-Specific Headspace Gauge for proper installation. Clean after each shot for the first five shots. Then clean after every five shots for the next 50 shots. Notes:Barrel will fit Savage large thread actions originally factory chambered for the Remington Ultra Magnum, Remington Short Action Ultra Magnum, Winchester Short Magnum, Winchester Super Short Magnum or Lazzeroni cartridges with a .550" or larger case head diameter.