I am having a custom 40X rifle built as we speak and I shoot USBR, I asked the same question to every person that I have met in person at matches and here is what I came up with. I am using a 40X action adding a 24" 16:1 Shilen Ratchet 4 grove with the Cryo treatment, it seems to be an underground favorite and performer. The unique rifling profile forces the bullet to engage the lands and grooves; I hope it works as well as it is supposed to. After talking to several gunsmiths I chose Gene Davis with Lamon Loggins a close 2'nd, if you want a precision rifle go with Davis for a full build if you want a little better price and want a just re-barrel and the stock inlet and bedded go with Loggins. I had little choice because all I had to start with is a receiver, everything else is custom hand built and tuned but I don't think your going this route with a squirrel rifle. I am curious how some of the smaller profile barrels on hunting/sporting rifles improve accuracy; I rarely get to see them due to the restrictions in most BR disciplines they banned. Good luck and let us know how your build works out, if you get a chance post a pic or two we are all about the DIY'ers and their results. "T"
Below I posted the Ratchet 4 Groove by Shilen; it is a cool looking profile and looks like it would work well.
Standard 6-groove Rifling--------------------------------Shilen 4-groove Ratchet Rifling
Edited by TONY Q.C.I.S., 01 February 2010 - 08:28 PM.