BMP only uses match grade cut rifled barrels for our gun packages. The first step in a accurate rifle build is a full inspection on the barrel before it ever gets put into the lathe. After the bore is cleaned we check for variances in bore diameters and any tight or loose spots throughout the bore. All of this is done by sliding lubricated lead slugs through the bore and using pilot bushings when there are dimensions’ issues in the bore. Second we inspect where the tooling from Barrel manufacture goes into the bore to ensure that portion of the barrel is not used. This tooling wear usually only effects the first .25-.75" going into the bore. All this is completed when the visual inspection portion is done with aid of a bore scope. Once the barrel meets our approval it is put in the lathe and dialing in process starts. I take my time on indicating our barrels in from the breech end of the bore in a benchrest style of chambering which i learned from one of the most well know smiths in the country. The last precision step is to fine tune the final adjustment in with a mitzotoyo .0001 indicator. This final step insures precision and makes the chamber job easier to check throughout the job that all the work is concentric and within .0002" of the throat and area just ahead. This process is necessary for the bullet to enter the bore perfectly centered so jacket material and bullets truly stays the way the bullet manufacture intended for top match grade accuracy. We also ensure proper alignment and how the chamber reamer is cutting with the ad of a Hawkeye Bore scope. Once head spacing is set from .001-.002" with chamber reamer and the go gauge then the throat is set to customer specifications of their loads desired cartridge overall length. Some calibers throat dimensions are built into our reamers for maximum performance. Finally, we clean up all edges and polish the chamber with 400 grit sandpaper for smooth feeding and good grip on your brass to eliminate bolt thrust. At this point the chamber job is done.