Jim, just a thought, could they machine the cylinder, cut it in half length wise, machine the interior, weld it back together and turn the welds off. Or start with square stock and than turn after it's welded back up. Is there any evidence on the original as to how it was made? The first thing I though of was it forged some how. Just checking.

I am using a chuck off a breast drill for an adaptor now, I use it with a new 1-1/2" bit. I want one for peg holes, if you make it longer I am wondering if a 12" long bit will have the the clearance and capacity in the boring machine? Tim