Barrel bent?

[J.Baker]

Thanks for the clarification. Is that why I sometimes see light flatspots on the action next to the recoil lug? Also didn't you have a photo of some guy that does a visual inspection looking down the barrel. If so what is he up to in that photo.

The guy you're speaking of, as Fred noted, straightens the barrel via looking through the bore. He looks through the bore at a special light box and then based on the shadows seen within the bore he knows where to tweak it to make it straight. The machine he's using is basically a bending tool to nudge the barrel in the direction needed when necessary. It's a fine art and a skill that takes lots of practice to master - which is why a lot of manufacturers don't bother straightening their barrels.

As for the OP's question about if the bore is bowed, the truth is that ever bore in every gun barrel is going to have some bow in it. You're drilling a hole through a 16-30" long piece of round bar stock and naturally the bit is going to drift a little as it travels that length. The smaller the bore diameter and the longer the barrel the more potential there is for drift as the bit's shaft is thinner and more flexible. Generally speaking most barrel makers end up scrapping one out of ever four .17 and .20-caliber barrels for this reason which is why most barrel makers charge more for those blanks.