Borescope Time: What am I looking at here?

[MDof2]

What appears to be a nearly perfect concentric ring about 5" to 6" inches downstream from the chamber.
This is a 6.5CM barrel, 26" long, heavy profile. Roughly 500 rounds through it. Shoots decent groups as it is now.

Local buddy thinks it may be from the pilot on the reamer that was used. I have no idea what it is, could be, etc. Drawing a blank / scratching my head myself.
Throwing it out in open waters for comments. Also planning to reach out to the manufacture (Howa) for comments from them as well and if they believe replacement is warranted or suggested. Two other Howa barrels I have don't have this.

Any ideas?

Still:

Video:

 

[tuckybill]

I think that is where the reamer caught a chip and gouged a groove while it was boring the barrel. Then the button was run through . I've got one just like that on a BA barrel for a AR. If you want to see a shocking barrel look down a Japanese T bolt. Mine looks awful. Shoots just "ok".

 

[MojoNixon]

I’d agree with the above. If you look close at the first pic there’s 5 or 6 more rings visible. Just not as severe as the first ring. I am a mechanical inspector. I look at and measure machined parts all day long for the past 39 years. I get paid to not miss stuff like this. Granted, generally not firearms related but both manned and unmanned space flight, radar parts for the FA 18 Superhornet, etc. I’d be ashamed if that got by me. I’ve seen good machinists quit for letting something like that get out.

 

[MDof2]

I could see a chip through a reamer or a button pushing one down the barrel, which would make sense, however this travels concentric up the land and back down through the groove. That's one hell of an accurate chip.

 

[Steel head]

It’s nothing as long as it shoots.

 

[THEIS]

Hi,

Its a mass production factory barrel, it is not going to be as clean as a premium barrel manufacturers products.

Sincerely,
Theis

 

[Steel head]

 

[cornhusker86]

Hammer forged barrel. Could be a witness mark from the mandrel.

 

[Steel head]

Hammer forged barrel. Could be a witness mark from the mandrel.

Seeing it’s in the land and grove that’s feasible.

 

[cornhusker86]

Seeing it’s in the land and grove that’s feasible.

I was going to say that it's the seam where the two pcs. of barrel are welded together, but I'm turning over a new leaf. Trying to be a kinder, gentler asshole.

 

[Steel head]

I was going to say that it's the seam where the two pcs. of barrel are welded together, but I'm turning over a new leaf. Trying to be a kinder, gentler asshole.

I like the two piece barrel hypothesis better!

 

[2aBaC̶a̶]

I was going to say that it's the seam where the two pcs. of barrel are welded together, but I'm turning over a new leaf. Trying to be a kinder, gentler asshole.

^^^^This, definitely this.

 

[Steel head]

Maybe friction welded sections of different twist to get a value version of gain twist?

 

[cornhusker86]

Maybe friction welded sections of different twist to get a value version of gain twist?

I'll stick with my original theory. OP's buddy had me for a second with the reamer idea, but that would only mark the lands, not the grooves.

 

[Steel head]

View attachment 7525366

I'll stick with my original theory. OP's buddy had me for a second with the reamer idea, but that would only mark the lands, not the grooves.

Exactly and it’s too far up.

 

[cornhusker86]

Exactly and it’s too far up.

This is why I don't clean barrels! If you can't see it, it's not there!

 

[Steel head]

I’ll tell you what bore scopes are fantastic at, looking into cases to inspect for possible case stretching and future separations.

 

[cornhusker86]

F'n A Cotton, F'n A

 

[MDof2]

Mentioned a couple times in another thread on the topic is Howa's are cold hammer forged. Likely part of the mandrel as mentioned by @cornhusker86
The other point that follows is, what's the problem if it shoots straight? Shoot it! I'm a fan of this philosophy for sure.

 

[MDof2]

I was going to say that it's the seam where the two pcs. of barrel are welded together, but I'm turning over a new leaf. Trying to be a kinder, gentler asshole.

Tig or Inertia Friction?

 

[cornhusker86]

Tig or Inertia Friction?

Oxy acetylene...

 

[1moaoff]

I was going to say that it's the seam where the two pcs. of barrel are welded together, but I'm turning over a new leaf. Trying to be a kinder, gentler asshole.

Beat me to it!

 

[1moaoff]

This is why I don't clean barrels! If you can't see it, it's not there!

Clean but don't look closely!

 

[FisherT&C]

Nice job cleaning your barrel, looks good.
That's just a button mark more than likely. That sort of thing is what lapping takes care of. In the case of a real production rifle you should shoot and clean incrementally for the first 50 rounds at most. Then just go in periodically to remove powder fouling with a mild cleaner like Hoppes 9 or Kroil don't try to remove every bit of copper it's like pissing on a forest fire. The barrel will get in a groove so to speak where it shoots predictably for awhile then needs powder fouling removed and it keeps going. A little bit of copper in that barrel will be beneficial.