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By tinkertoy92
#13639 Got a query for you guys- one of my other rifles is a 6.5 creedmoor lr-308 that I built a while back, and when I was prepping some brass I noticed that there's helical score marks on the case body. Just curious if anyone knows what would cause this and ifs a sign of something I should be worried about. The rifle is very accurate and I am not running it at excess pressures. The best thing I can think of is that right now its ejecting harder than I like (the lugs on the barrel extension leavery score marks on the neck) because I'm not using an adjustable gas block (yet)...
2017-03-23 15.54.36.jpg
2017-03-23 15.54.36.jpg (593.12 KiB) Viewed 4022 times
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By mbogo
#13642 'Helical' means in a spiral, like rifling. Are the marks spiraling around the case or are they ring marks circling the brass?

From the photo, it looks more like your chamber may have tool marks from the chamber reamer.

Does it happen with factory rounds? Have you looked at the chamber under strong light?

mbogo
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By tinkertoy92
#13643 They definitely spiral- and it's on every case ive fired through it. I cant say for factory ammo- everything I've put through it I loaded. When I inspected the barrel when it came in I couldn't see any tool marks in the barrel... that said I didnt inspect it with a bore scope. I will say that the barrel is very accurate and super clean with the loads I'm putting though it... like whether 10 rounds or 30 ( I've never shot more than 30 in a range session with it) the 2nd dry patch comes out clean. If the marks on the brass are aesthetic it's not a big deal to me, I've just never seen that before and didn't know if maybe it was a sign of a deeper problem.
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By mbogo
#13644 I still suspect the chamber has tooling marks from the reamer. Pull out the rear pivot pin and remove the BCG. Shine a light from the muzzle end and look for spiral marks in the chamber.

Do the marks appear when you extract an unfired case too, or only on fired cases? Are they engraved or proud?

The scratches on the case necks can be fixed by lightly stoning the offending lug(s) a bit.

mbogo
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By tinkertoy92
#13645 Thanks- I'll polish the edges on the 2 right side extension lugs. Any marks on the cases the cases are only the result of firing. The marks on the cases I would say look more like a scuff than engraving
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By mbogo
#13649 For the third time, check the chamber for tool marks.

mbogo
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By tinkertoy92
#13691 After a more thorough inspection of the chamber, there are some light tool marks in the chamber- if just chamber and extract fresh brass, there is no noticeable chafing onthe cases, just due to firing
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By mbogo
#13692 Contact the barrel make ASAP. They should a) pay for return shipping, b) replace the barrel, and c) pay to ship it to you. This was a manufacturing defect.

mbogo
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By tinkertoy92
#13698 If it feeds and extracts reliably, and shoots accurately how big of a deal is it?
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By Rangemaster1
#13699 By the appearance of the marks, the chamber wasn't polished after reaming. And, the reamer was getting dull. Some 400 grit wet/dry cloth wrapped around a slotted dowel will polish it very nicely. Better done with the barrel off the upper, but it can be done with the barrel on. Just needs a longer dowel. A good hand drill is , of course, required to drive the dowel. Just don't over fo it. Too much polishing could cause the chamber to become oversized. Not good.