Can you show me pictures of burnt out barrels?

[Alex Wheeler]

Bore scopes can make something you cant measure with a .0001" indicator look huge. Thats a fact. To the untrained eye a bore scope can really get in your head. But the only way to get a trained eye is to use one. Unless you have the barrel in the lathe with a .0001" indicator in it Im not sure how you can learn the size of the thing your looking at. Here is some food for thought. The micro grooves in the barrel from the lapping process cant be measured with the best .0001" indicator on the market. The height of the land is .003-.004 and it looks huge. A case drug down the side of a fresh chamber will leave a mark that looks terrible, again it cant be measured. They are a wonderful tool and I recommend owning one, but reserve opinions until you know what your looking at. Never hesitate to send a picture to your smith and ask what your looking at. If you dont trust his opinion, you shouldnt have used him. As said, the target never lies.

 

[martin22250]

Old ppc barrel i cut in half with the bandsaw

 

[JohnKielly]

Here's how they do it.

 

[B Nettesheim]

Here’s a picture of a burnt out barrel

 

[3Sigma]

Bore scopes can make something you cant measure with a .0001" indicator look huge. Thats a fact. To the untrained eye a bore scope can really get in your head. But the only way to get a trained eye is to use one. Unless you have the barrel in the lathe with a .0001" indicator in it Im not sure how you can learn the size of the thing your looking at. Here is some food for thought. The micro grooves in the barrel from the lapping process cant be measured with the best .0001" indicator on the market. The height of the land is .003-.004 and it looks huge. A case drug down the side of a fresh chamber will leave a mark that looks terrible, again it cant be measured. They are a wonderful tool and I recommend owning one, but reserve opinions until you know what your looking at. Never hesitate to send a picture to your smith and ask what your looking at. If you dont trust his opinion, you shouldnt have used him. As said, the target never lies.

Good points here.

I use a laser microscope at work. It can reliability measure to the tenth of a micron. A highly polished piece of steel looks like a pile of rocks, a speck of dust is a giant wire across the screen. It takes a lot of trial and error to understand not only what you are looking at and measuring, but to also know if it really matters.

FWIW, I just use the borehole to check cleaning progress. I'm not good enough to use it to gauge lifespan, and let velocity and target performance tell the tale.

 

[bobm]

Old ppc barrel i cut in half with the band saw
View attachment 1264480

I did the same thing when my first 7mm-08 barrel quit shooting good. It was an M700 BDL varmint contour chrome moly used for silhouette. I got 4560 good shots and it went bad during a match. A benched group later at 500 meters measured about a foot across. A 7x loupe was used with my pocket Sony camera.