Indicating a bore

[holstil]

I had a Cooper chambered in 308. I was having issues reloading for it but took it to shoot my first match anyway. I was brand new to competitive shooting and Greg Culpepper took a look at it and found that the chamber was oversized. He let me shoot some of his ammo, I shot a 8.6" group at 1000yds with what turned out to be a chamber .014" oversized just ahead of the web. The cases looked funny all bulged out. Some bulged evenly most on one side. I sent it back only because I couldn't get more than 3 reloads from the brass. After I got it back with a better chamber I shot it in 3-4 more matches and never shot a group smaller than about a foot. Even with his ammo I never could find a good load at 200yds for it after that. No matter, it shot great with a nasty sized chamber. Go figure.

Now I'm curious, why do a lot of us indicate to a nats a$$ then want the reamer to float rather than aligning the tail stock? I guess it takes more chance out of play. I would like to chamber with a hand drill and a barrel vice to see the difference.
My experience is limited to about 20 barrels but so far, I haven't found three places anywhere on a barrel, any barrel, to be coincident to one another to indicate that close to.

 

[sailhertoo]

I had a Cooper chambered in 308. I was having issues reloading for it but took it to shoot my first match anyway. I was brand new to competitive shooting and Greg Culpepper took a look at it and found that the chamber was oversized. He let me shoot some of his ammo, I shot a 8.6" group at 1000yds with what turned out to be a chamber .014" oversized just ahead of the web. The cases looked funny all bulged out. Some bulged evenly most on one side. I sent it back only because I couldn't get more than 3 reloads from the brass. After I got it back with a better chamber I shot it in 3-4 more matches and never shot a group smaller than about a foot. Even with his ammo I never could find a good load at 200yds for it after that. No matter, it shot great with a nasty sized chamber. Go figure.

Now I'm curious, why do a lot of us indicate to a nats a$$ then want the reamer to float rather than aligning the tail stock? I guess it takes more chance out of play. I would like to chamber with a hand drill and a barrel vice to see the difference.
My experience is limited to about 20 barrels but so far, I haven't found three places anywhere on a barrel, any barrel, to be coincident to one another to indicate that close to.

From what I understand, you only need one place on the barrel. The first 3 inches where the chambering is taking place in relation to the bore.