Gunsmithing Visually identify button rifle vs. cut???

[Maddy]

How can one identify if a barrel is button rifled or cut rifled? What do you look for? Thanks.

 

[padom]

you won't be able to tell just by looking at the barrel.

 

[Changed]

Content removed by poster.

 

[bohem]

I ordered a button rifled barrel and a cut rifled barrel. The button rifled barrel exhibited notable eccentricity. It was very clear it was not completely round. I asked the maker (PVA), and Josh said it was a result of the button rifling process. Every barrel making video I've seen shows the factory rifling a raw blank. Then contouring. But, I presume the barrel maker would know better than I.

Just to clarify, your CONTOUR had eccentricities not your bore where the bullet goes through. This was an issue with the former barrel maker having problems with their contouring setup. It had nothing to do with the button vs. cut process and everything was on the OD of the barrel.

Two things to that:

1) That barrel maker is no longer supplying blanks to us.
2) Based on the back and forth that I had with them over this problem the blanks we are using are cut to a very specific print that also includes several GDT callouts for eccentricity and cylindricity. The contour is largely invisible to how the rifle barrel shoots, it's more asthetics and weight. We now track that and reject anything that fails to meet the print because I don't want to go through the hassles of holding out of round barrels as well as explaining to customers that the barrel is actually fine. Besides, for the money involved I really shouldn't have to tell people it's fine just shoot it.



To the OP: By eyeball it's very difficult to tell. If you knew what the button looked like you might be able to tell via bore scope. I can tell if I slice a slug off a barrel and put it up on the 20X projection on the optical comparator because I have the print for what the buttons look like and I can see tiny details between what the button has and what cut rifling has.

 

[Changed]

Thanks for the clarification, Josh. You are correct. I misunderstood your explanation. I took it to mean that all button rifled barrels exhibit this eccentricity.

 

[Maddy]

Thanks for the info. I always wondered if there was a way to tell

 

[bohem]

If the blank was not lapped then it's much easier to tell but for a high end button barrel the interior is much like the performance. It looks, behaves and shoots identically to the cut rifled sisters.