WTF is this on rifling?

Durable Gun

Lil-Rokslider
Joined
Nov 4, 2025
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164
Hello everyone, I went with my friend to the range. He has a Tikka CTR chambered in .308. He is not the best of shots but he isn't bad. I was watching his groups land and they where terrible. Like 6 + inches in sporadic patterns. I checked his action and scope ring screws and his action screws needed a bit of torquing to spec. He proceeded and his groups did not improve. I asked if he ever cleaned his bore and how many shots down the tube? His reply was 200 or so rounds fired and never cleaned. I originally suspected that his gun needed a good clean and that his gun didn't like the ammo he has been using. (The only factory ammo he has tried) . He did say that it used to shoot well when it was new. How well? I can't tell you myself. I took his gun home with me to inspect his bore and I found 2 concerning things that I haven't seen in bores. 1 - deep marring at the beginning of rifling at end of chamber. 2 - many what appear to be very fine circumferential hairline fractures along his bore. Any help would be appreciated. Thx
 

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Ive seen barrels with insane tooling marks way worse than that shoot legit 3/4" 10 shot groups.

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Have you seen them with marks that can't shoot?
Personally no.

Im not saying it doesnt happen, but I havent personally seen where a rifle was a bad shooter and tooling marks in a barrel wound up being the issue.

There are plenty of other guys on here with more extensive gunsmithing knowledge on here. Im sure some will chime in.

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I did shoot it. My groups where better. But not by much. Arken scope and mounts. Cheap shit. I did torque everything down to specs. Maybe the scope is crapping out and not holding zero.
That CTR should drive tacks. Did you shoot it? What scope and mounts?
 
The chambering reamer that was used was toast or it grabbed a few chips and chewed up the throat. Are those marks on only one land or all of them? The rest of the bore looks fine. The throat is the issue.
 
The chambering reamer that was used was toast or it grabbed a few chips and chewed up the throat. Are those marks on only one land or all of them? The rest of the bore looks fine. The throat is the issue.
All but 3 lands. Thanks for the feedback.
 
I’d ditch the bore scope.
If the barrel doesn’t shoot, it doesn’t matter what it looks like.
Take everything apart. Clean, torque and witness mark to make sure the fasteners don’t move.

Get a couple boxes of Federal Gold Metal Match 168 SMK and try those.
If it still won’t shoot, I’d say you need a barrel.
 
Arken scope and rings. I’m sure some have positive experiences with them, that would be my ‘primary suspect’ along with something being lose. The bore / throat area are fairly typical for a mass produced factory rifle.
 
The chambering reamer that was used was toast or it grabbed a few chips and chewed up the throat. Are those marks on only one land or all of them? The rest of the bore looks fine. The throat is the issue.

I throated my Shaw 223ai barrel to be able to load long.

Groups shrunk from 1moaish during load development to .5moaish.

Could just cleaning up a crappy throat due to crappy reamer do this?
 
I would start with cleaning and torquing all the fasteners. Especially if it was new when he bought it.
Also the scope could be bad internally. Ive seen even high end scopes throw shots around
 
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