determining the straightness of a bore.

[EC121]

I saw a Pedersoli video where they were straightening their barrels. The man looked at a light(window with a straight crosspiece) then had a gear driven bender with a handwheel that he used to bump the barrel until the bore was straight. However if is that far off, it sounds like the exterior is the problem.

 

[beardedhorse]

Have a .60 caliber, 48 inch swamped Don Getz barrel serial no. 1770. Got to be 40 years or so since I traded a longbow for it. Flats on the muzzle end don't match so can't fix with run out flat placed up or down. Run out might not be the problem. Uneven milling of flats probably is. Jack Brooks has a tree outside his house with a crook in it for bending a barrel. Also a trough for charcoal blueing barrels. Both too scary for me to try as the barrel is already inlet into a $300 curly maple stock blank from Freddie Harrison of Tenneesee. Am switching from the flint breech plug that came with the barrel to a hooked breech. On bucket list to finish along with Bill Large barrel Hawken but don't want finished rifle that shoots weird (catywompous windage and elevation) at different ranges. Cable or string through bore with a bow is an old Hacker Martin trick to check straightness of bore. Once you file dovetails for sights and barrel lugs, you are committed to using the barrel in whatever orientation it is in.

 

[Billy Boy]

Thanks Dave, I tried your simple suggestion of just looking down the barrel at a white surface, and it looks straight. I had been looking through the bore at bright light, or outside in the daylight, and that wasn't as clear. So that was helpful. I couldn't detect any noticeable run out in either breech or bore, but I should break down and buy a vernier caliper.... I'll talk to Colerain and get their imput. I don't have a laser or straight steel rod of the appropriate size around, but I can check with friends. Thanks again.

Hang a wire or draw a dark line on that white background. Look thru the barrel while slowly rotating it. If the image of the wire/line remains straight the bore is straight. If it suddenly ‘bends’ the barrel is bent and the bend in the line image seen thru the barrel shows you where. It has worked for me many times.

 

[rmann]

Hang a wire or draw a dark line on that white background. Look thru the barrel while slowly rotating it. If the image of the wire/line remains straight the bore is straight. If it suddenly ‘bends’ the barrel is bent and the bend in the line image seen thru the barrel shows you where. It has worked for me many times.

I'm trying Billy, but it is hard to rotate the octagonal barrel smoothly and keep a steady eye on the line through a .40 bore... But it looks straight to me. at least it is helpful to see 2 balanced 1/2 spheres as I rotate and hold on each flat.
Thanks, and thanks to all for your helpful input. And I do have a message in to Colerain, to get their input on grinding discrepancies.

 

[Billy Boy]

I'm trying Billy, but it is hard to rotate the octagonal barrel smoothly and keep a steady eye on the line through a .40 bore... But it looks straight to me. at least it is helpful to see 2 balanced 1/2 spheres as I rotate and hold on each flat.
Thanks, and thanks to all for your helpful input. And I do have a message in to Colerain, to get their input on grinding discrepancies.

The balanced halves tell me the bore is straight. If the ‘line’ seen thru the bore didn’t bend at a certain point, its’ straight. If the bore is centered in the
the blank is another issue bot not a big one

 

[rmann]

OK, Thanks, I tended to think so. But I did email Scott from Colerain yesterday, and he called me this AM, and advised me to send it in so he could examine it himself, and remedy as necessary. He was very responsive, just as the Col. expected. I should have talked to him before starting this thread, but learned a lot though everyone's input. So thanks to ALL!

 

[SDSmlf]

Great. These guys and most other suppliers stand behind their products. Much easier to just contact them first. And now you will find out if your barrel is straight without sacrificing any chickens or howling at a full moon. Let us know what you find about about your barrel. Talked to one barrel maker who stated that it wasn’t that rare to get complaints about swamped barrels not being straight, although it was rare to find one actually bent, unless there were tire marks or some other obvious physical damage to packaging.

 

[rmann]

Thanks for all your good replies, and to Colerain for their quick response to send me a new barrel. I hesitated to send it to them if I couldn't verify it was a little bit bent. But once I contacted Scott, he readily encouraged me to send it in for his assessment. In just one week I had a new one at my door! H e affirmed it was slightly bent, and made sure to remedy it. I really appreciated his care. It is tough, when a barrel leaves his shop most likely true, but between the retail shop and me, and the shipping and handling in between, who's to say where the responsibility lays. But Colerain bore it, so I credit Scott and company to maintain satisfaction overboard. So, I am happily letting you know the end of the story.