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  #16  
Old 01-26-2021, 12:07 PM
ceresco ceresco is offline
 
Join Date: Oct 2009
Posts: 8,026
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I would not straighten a barrel using the exterior dimension. The bore does not necessarily line up with the exterior. The standard is to optically check straightness and go from there. Anyone can use the optical method. It is actually pretty easy. You simply view a lattice through the bore and look for curvature. I use the siding on a building--and it works! Unfortunately, you need a straight shot through the receiver which leaves out the M1 unless the barrel is removed or some complicated mirror system is used. Let us know how this ends. Good Shooting. ..