I have a buddy who was recently given a rifle and has no idea what it is. its a very heavy .308 caliber barrel on a winchester action and a target style stock. but no designation anywhere on the rifle. its a long action and the bolt face is .540 so I am assuming its a 300 win what was used for bench rest back in the day. I told him to go have a gunsmith run a go/nogo 300 win in it and see if its head spaced for that, that would at least get us in the ball park, but those are head spaced off the belt right? so it may be an old wildcat or something. If he had someone take a mould of the chamber we would know is that the only way to find out? is there a way to do it himself?