well i straitened the barrel on my H&R 357 MAX today. this is how u check
for barrel straightness. to check the front muzzle half of your barrel, insert
a empty unprimed brass in the chamber and point the chamber at a bright
light, sky, or snowbank. the barrel has to be clean. u will see black and white
rings. if your barrel is straight the rings are all centered. the biggest ring is closest
to your eye and the smallest ring is the halfway point of the barrel. to check
the breach end of the barrel u have to make a light button that just fits in the bore.
the button has a .100 thou hole
in this pic u can see the small ring is not centered but down low. a photog i'm not.
the pic is not as pronounced as in real life. anyhow u get the drift