Chatter marks in new CHF barrel

[Androctonus]

I'm going to contact the manufacturer, but I was wondering if anyone's seen anything like this in a new CHF barrel before. Looks like tool mark chatter. Have read somewhere that CHF can have what look like tool marks, but it doesn't give me a warm fuzzy feeling. I won't disclose the manufacturer openly (PM me about it if you want).

[26 Inf]

I'm going to contact the manufacturer, but I was wondering if anyone's seen anything like this in a new CHF barrel before. Looks like tool mark chatter. Have read somewhere that CHF can have what look like tool marks, but it doesn't give me a warm fuzzy feeling. I won't disclose the manufacturer openly (PM me about it if you want).

Androctonus: Are you any chance a dermatologist? I'd like to know, because if you are, I want you to do my yearly screening for bad things that pop up from too much sun.

I've seen this many times and most often in hammer forged barrels. The hole is drilled in the barrel then it is hammered around a reverse rifled mandrel and chamber. A button cuts the rifling in the barrel and would remove the drill marks, hammer forging often does not remove the lines, just mashes them flat but smooth. The question is, do the rings you see do any harm? Does it shoot well, does it increase fouling? In the barrels that I have with the marks they shoot just as well and foul no more than barrels without the lines.

(Second Post on: https://www.ar15.com/forums/ar-15/Ne...ore/12-634632/)

https://photobucket.com/gallery/user...MS5qcGc=/?ref=

https://photobucket.com/gallery/user...LmpwZw==/?ref=

Additional:

I recently attended a precision rifle class where this very topic was discussed. The instructor was a long time precision rifle builder and gunsmith that worked for years at (among other places) Surgeon rifles (pre-merger). He stated that the new bore cams are affordable, and as such allow non-versed rank amateurs to view the other side of precision chambers. The problem as he saw it, was that folks just don't know what to look for, what to ignore.

He said that he would rather a new bore scope owner observe, shoot, and observe more. Don't think that imperfections in the machining process will likely have any real effect on accuracy. Small tooling marks and gouges are routine, even on high end chambered barrels. The trick is, to keep shooting as you always have, observing how the rifle performs, not the condition of the chamber and bore. Only when you notice a degredation of repeatable accuracy should you begin to employ these tools; and only when you have a good idea what it is you're looking for. Education materials are - for now, slim concerning these tools.

This was in the final briefing for the class, and was more in passing than most anything else. He was impressed with the new generation of the Lyman bore scope, and said that it was almost too good, at too low a price. Loose quote: "Now, everyone that has one of these new higher resolution gadgets will get swamped in worrying about something that they would have been blissfully ignorant of before." His point was that they are useful, for knowledgeable gunsmiths, and for general inspection. The truest test of a chamber isn't it's machined perfection, but how well it puts repeated hits downrange.

He did say that you will know what to look for if you ever see a worn out barrel through one. One was all it would take. Look at a known "shot-out" barrel, and you will see the obvious problems a bore scope will help you keep an eye out for.

Perhaps it would help to compare these observations with a barrel that has several hundred or thousand rounds through it?

Oh, (take this with a grain of salt, for my memory may be off here, but) he also said that every barrel treatment looks different under magnification. Chrome lining in the throats starts to show cracks long before it becomes an accuracy issue, whereas in a nitrided barrel, cracking is indicative of fatigue that should be more closely observed. Stainless and CROMO steel untreated barrels were best to cut new teeth on because they are typically more honest indicators of barrel life than the treatments, which change surface hardness in sometimes strange and irregular ways.

http://www.65grendel.com/forum/showt...and-what-is-OK

[Androctonus]

Thanks, 26 Inf. Haha, no, I'm not a dermatologist. I'm just very detail oriented and thoroughly inspect any new firearm/upper. Sounds like it probably won't be an issue. I found that linked thread from arfcom before posting here. That second post is informative. But, the poster mentions that chrome lining may cover up any marks from the boring bit. Both the barrels in question are chrome lined. That doesn't mean there's something wrong though. Hopefully, I'll hear back from the manufacturer tomorrow and confirm that this is a normal appearance for their barrels.

[hk_shootr]

Quit inspecting it for flaws and shoot it.
If it shoots poorly, address the issue

[Androctonus]

Quit inspecting it for flaws and shoot it.
If it shoots poorly, address the issue

Just finished setting up the rifle and about to go put a few hundred rounds down the pipe. The manufacturer said the barrel looks fine.