Bore slugging or determining the dimensions of the bore of a rifle has come up a few times in discussions, here's one way to do it:
Get some soft lead egg sinkers, make sure they're not the non-lead kind, they're too hard. Follow the basic directions in the link below. I like to pancake the sinker between dowels, you get a much nicer slug than one that you just push thru the bore, do one near the muzzle and another near the throat, push it out the near end, that way you'll know how much bigger it is at the muzzle than at the other end, it will likely be about .0005" tighter at the chamber end.
http://7.62x54r.net/MosinID/MosinSlug.htm
Egg Sinker Size:
Size 10
For use in .270, 7mm, and .30 Calibers
Size 9
For use in .338, .348, 38/.357, and 35 Calibers
Size 8
For use in .41, .44, .45, and .475 Calibers.
As with everything else use good smart safety procedures, like starting with checking to see if gun is loaded..........
Get some soft lead egg sinkers, make sure they're not the non-lead kind, they're too hard. Follow the basic directions in the link below. I like to pancake the sinker between dowels, you get a much nicer slug than one that you just push thru the bore, do one near the muzzle and another near the throat, push it out the near end, that way you'll know how much bigger it is at the muzzle than at the other end, it will likely be about .0005" tighter at the chamber end.
http://7.62x54r.net/MosinID/MosinSlug.htm
Egg Sinker Size:
Size 10
For use in .270, 7mm, and .30 Calibers
Size 9
For use in .338, .348, 38/.357, and 35 Calibers
Size 8
For use in .41, .44, .45, and .475 Calibers.
As with everything else use good smart safety procedures, like starting with checking to see if gun is loaded..........
Just thought I'd kick in that the chamber end on custom barrels is determined(by the maker) by which is the 'tight' end. On a custom tube, the muzzle is tighter and the other end marked to be the chamber end (brand name, twist, caliber, material made of). When I slug a factory barrel (I have never had the need to slug a custom as they are within four places to the right of the decimal point, .0001) I cast a slug that is .009 to .010" bigger than bore diameter. I use Cerosafe, a chamber casting lead alloy, quit soft stuff. I grease the slug liberally with Rig Gun Grease, oil the bore well with tool and instrument oil and push (with as even force as possible) from chamber to muzzle. This method has worked well for me many years. It was taught to me by the machining/custom alterations instructor at MCC.
