Barrel Pictures and a question about marks in barrel

[csmith]

Good day, horde.
I wanted to tap collective expertise on what I'm seeing. The Grendel has made me an learn a lot on accuracy work, etc.

As part of the adventure, I bought one of the teslong endascope.

Barrel is heavy profile criterion, 12.5 inch with carbine + 1 inch gas system about 800 rounds through it. Not abused. The most that I have done is a 20 round string and then allowed cool down.

These lines are approximately 2 inches forward of where the rifling starts in the chamber.

I appreciate inputs from others with more experience looking inside their bore with a camera.

Chad2020-07-26-08-00-38.jpg2020-07-26-08-01-02.jpg2020-07-26-08-00-38.jpg2020-07-26-08-01-02.jpg

[A5BLASTER]

Did your 20 round string produce good groups?

If yes. Throw the bore scope in the trash can.

[csmith]

Well, the 20 round group was about 2.9 MOA; but that was last October. I'm now seeing some pretty wild gyrations in accuracy.

Shooting handloads, 123 SMKs all bullets are weighted and sorted as well as powder charges measured.

Last 2 sessions got me 1.4, 1.3, 2.0, 1.1, 1.3, 2.9, 1.2 MOA. This is will 20 minute cool down off a bag, barrel is bedded, NM carrier, Geissele trigger, etc.

I shot for a collegiate rifle team so I'm generally pretty good at figuring out when I'm the one pulling the shot and the randomness on the groups made me wonder if others had seen similar marks in a barrel.

[FRB6.5]

I have a Weatherby Vanguard Varmint in .223 that has those spiral markings but far far worse. It looks like it was rifled with a rototiller. It however does shoot just under sub-MOA meeting their guarantee.

I now save the bore scope for when I suspect there may be an issue, it's too easy for something like this to get into your head. I will point out your bore looks really really clean, how is the accuracy with some copper left in it?

[csmith]

Well, I've changed several variables this weekend. Larger handguard and decided to clean the bore. I've got some load work to do next weekend and try some 130 grain RDFs as well so I'll find out over the next couple weekends. Thanks for the feedback.

[tdbru]

csmith,
I suspect those cross hatch marks are remnants of the deep hole drilling that didn't get polished/lapped out. perhaps a chip got caught in the deep hole drill and scored the barrel. I've seen far rougher looking barrel shoot well, so, in my limited experience, I'd look somewhere else if accuracy isn't what you want, though the barrel is certainly one of the first places to look into. Have you sent these photos to Krieger and asked them about it? If they think it's their problem they might do something about it.
-tdbru

[stubshaft]

csmith,
I suspect those cross hatch marks are remnants of the deep hole drilling that didn't get polished/lapped out. perhaps a chip got caught in the deep hole drill and scored the barrel. I've seen far rougher looking barrel shoot well, so, in my limited experience, I'd look somewhere else if accuracy isn't what you want, though the barrel is certainly one of the first places to look into. Have you sent these photos to Krieger and asked them about it? If they think it's their problem they might do something about it.
-tdbru

What he said!