how to fix a curved hole

[12bolts]

Maybe, it would be a bit more work, but make your cutting end of the D bit larger than the shank. Then you could slide sleeves on behind the drilling head that fitted the bore and would help to keep it straight.

Cheers Phil

 

[elysianfield]

12 Bolts is right on the way to 'straighten' the bore, but I'm curious as to how it got to be off center. If you bored the original barrel the bit, pilot or not should have followed the original bore. I've always used piloted bits for liner installation, but I can't imagine the bit getting that far off center from the bore. (A photo would help.)

I'm curious as to how this will work out. So please document the process and the results, good, bad or otherwise.

The original bore probably had the curvature to begin with...Gundrilling is an art, not a science...I used to make rifle barrels, and have some experience with the topic.

 

[george wilson]

As mentioned,you need to use a piloted drill. End milling out the muzzle end and using a D bit might get it back on center,but ONLY if you use an outboard cathead chuck,and get the barrel true running before end milling for the D bit. If you get the end mill started untrue,the D bit will just follow it.