The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

dodgyrog wrote:The last time I set a barrel blank up through the headstock took well over an hour to get the bore run-out less than .0001" (for metric work it out yourself!).
Similarly, setting up to thread for a moderator takes nearly an hour.
Use only 4 jaw chucks to get the best result.

Sorry to run off-topic a little here, but over what length did you clock for the concentricity of the bore axis? I've often wondered what was the general accepted length? Also, I am assuming you clock from something sticking out of the bore itself (dowel/plug gauge etc) as the barrel blank is running through the headstock?

I've always been curious about how accurately barrels need to be setup, I often have to clock in work on the cylindrical grinders at work and this same thought always springs to mind every time I come to clock in

billgatese30 wrote:

dodgyrog wrote:The last time I set a barrel blank up through the headstock took well over an hour to get the bore run-out less than .0001" (for metric work it out yourself!).
Similarly, setting up to thread for a moderator takes nearly an hour.
Use only 4 jaw chucks to get the best result.

Sorry to run off-topic a little here, but over what length did you clock for the concentricity of the bore axis? I've often wondered what was the general accepted length? Also, I am assuming you clock from something sticking out of the bore itself (dowel/plug gauge etc) as the barrel blank is running through the headstock?

I've always been curious about how accurately barrels need to be setup, I often have to clock in work on the cylindrical grinders at work and this same thought always springs to mind every time I come to clock in

I use a DTI with a three-inch stylus - to get beyond the first inch or so of barrel, which isn't always representative due to the lapping process. Some barrel makers actually put a small saw-cut near the muzzle to indicate that at least this amount must be cut off.

Reamers and the other kit I'll source as and when I need it. I've long since past my stupid phase of needing the next new calibre. Also I'm fortunate in that I have access to 4 Boxford lathes.

Both hack jobs were done by supposed well respected gunsmiths so I've decided to do the basics for myself. At least I'll know that it's been done right. Time and money aren't really an issue.

Thanks for the info.