Chamber question

[Slimfinn]

So ive started messing around with my 243 and i noticed these tick marks on the shoulder of the cases after firing. First what are the options to cleanup the chamber i do not have a scope to look in it right now, and are these tiny marks going to affect anything like premature brass wear or anything?
Its a used Browning X-Bolt in 243 i picked up a year or so ago at a pawn shop.

 

[mjcmichigan]

My first reaction, is it’s coming from the loading action. If it was in the chamber, it would be more of a tiny dent..

I’m not a gunsmith. I did pick up a borescope on Amazon for $60.
If you do, you was a rifle borescope with a 90 degree mirror. At that price they are typically USB devices. There are more expensive stand alone units. I think Lyman makes one still.


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[elkeater2]

I think borescopes with 45 degree mounted mirrors give a 90 degree right angled view of things like we want. Kinda confusing. A 90 degree mirror will give you a selfie. I do think those nicks on the case shoulder must be from feeding rather than the chamber. The x-bolt magazine may be the culprit. EE2

 

[Slimfinn]

I've checked it is something within the chamber. I've taken a fired brass, made sure it was smooth, dropped in the chamber and closed the bolt, then eject. When they come out you can see and feel the tick marks. Looking in I think I can see something but it is hard to get the lighting at the right angle and look in at the same time. I've found a flex-hone for the 243 chamber, I might order and give it a try

 

[mjcmichigan]

I think borescopes with 45 degree mounted mirrors give a 90 degree right angled view of things like we want.

Thanks for the correction!


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[gbflyer]

I don’t think that will cause you any heartburn. If it’s feeding, shooting, and extracting properly I’d leave ‘er be.

 

[Nimrod84]

I don’t think that will cause you any heartburn. If it’s feeding, shooting, and extracting properly I’d leave ‘er be.

+1

Think the flexhone would be too aggressive for that sort of burr. You really don't want to change the chamber's shoulder angle.

If it really irritates you, I would suggest getting some 1000+ grit paper on an appropriately sized wood dowel or even Flitz / Rouge / etc. on a converted case (case with a means of rotating - usually a rod attached in or through primer hole) and just take a light pass or two. Again, you don't want to change the shoulder angle or remove metal but just break the sharp points that dig into the case.

I had a similar burr on a 30-06 Kimber 84L but it was lower on the body and it was affecting feeding after firing - wood dowel and paper (https://www.brownells.com/gunsmith-tool ... 25651.aspx) took care of it with about 5 light passes but I probably could have stopped at 2 or 3 passes.

Another area where a burr required attention was just before the lands. It was cleaned up with a chamber reamer in two passes with light pressure.

 

[Slimfinn]

Yeah i might just leave it, that is what i was concerned about was messing around by the shoulder area. I'll see if it keeps bothering me, and how well it ends up shooting and go from there.

 

[elkeater2]

I suggest verifying the cause before polishing or honing. You should be able to see it. Maybe use a sharpie on the outside of a case, chamber it, extract it but don't eject it. Rotate it 180 degrees and do it again. If marks show on opposite sides you'll know. Handy for me are the little lights like they sell in auto parts store that have a little LED head on a flexible stalk and a magnetic base. You can see a lot of a chamber on a bolt action with those. Good luck. EE2

 

[elkeater2]

Sounds like your pretty sure it is in the chamber. If you don't know about this guy - http://varmintal.com/arelo.htm - there is a ton of information on his page. He's a retired engineer with access to engineering type equipment and uses it for all things gun related. The level of detail he goes into is amazing but a little tedious sometimes. Anyway, if you go to the link suggested, First read the link "Rifle Chamber Finish" on the left side - where I learned more about causes for case head separation than I even suspected. If you wade through that whole thing you find out that a case needs to move some upon expansion and firing, or else it will grab a rough chamber and stretch the case head back to the bolt face too much. Then, if you buy into his explanation, go to the link at the top for "Polishing my Chambers". I have done what he says and it worked for me. BTW - don't get lost in there! A guy could spend several days and never make it back to our forum here. EE2

 

[Nimrod84]

Handy for me are the little lights like they sell in auto parts store that have a little LED head on a flexible stalk and a magnetic base. You can see a lot of a chamber on a bolt action with those. Good luck. EE2

Those lights (https://i.ebayimg.com/images/g/KhoAAOSw ... s-l500.jpg) are great, I also use dental mirrors on a stick (https://s.yimg.com/aah/dentakit/dental- ... ror-24.gif) and different bore mirrors to look around (https://i.ebayimg.com/images/g/tTQAAOSw ... s-l300.jpg or a locally made variation of https://estore.thecmp.org/Catalog/Item/PS099PBRSKWV).

I've never gotten a good view of the shoulders with my tools and longer 30-06 length cases - might just be my eyes or the length of the cases. OP would probably have to play with shinning light down the bore and or using a white patch just pushed into the bore to get some views of the shoulder.

A bore-scope with a built in light and 45 degree mirror would be the way to go in my humble opinion for viewing small burrs on the shoulder. There are other ways of diaganosing them as EE2 noted.

 

[mjcmichigan]

BTW, that flashlight should be in everyone’s range bag. Anytime something doesn’t feel right, barrels should be check for clearness and I find that light is quick and easy if there is an obstruction ...


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[mjcmichigan]

Here’s the teslong rifle bore scope on Amazon. $50

https://www.amazon.com/dp/B07XDYN296/re ... UTF8&psc=1


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[Slimfinn]

Thanks for the info, i just ordered one