What is this stuff in my barrel's chamber?

[AznTactical]

10.5" Odin Black barrel
Fast forward to 42 seconds. What is this? Video was taken after cleaning with BoreTech C4 several times. It is located on the body location of the chamber right before it transitions to the shoulder.
.300 blackout barrel. No more than 70rds thru it. Light strike, doesn't go into battery 75% of the time, hard to extract round when light striked and/or when it doesn't go into battery. Almost have to mortar it to get the live round out. Happens to all factory and handloads.

For comparison here is another of my 10.5" Odin barrels that has over 1,500rd thru it. ZERO issue with this barrel. 10.5" Odin SS barrel

 

[hkguns]

Those look to me like carbon infused tooling marks or Harley tracks to me. Maybe someone else has different ideas.

 

[Supersubes]

Looks like the reamer that wasn't cutting properly in those areas.

 

[bfoosh006]

Ooof.... what specific ammo ? Subs? supers ?

 

[papershredder]

To add to @Supersubes' post. Gaulding, happens with dull/chipped reamers, or metal shavings getting caught in between the reamer and barrel by either feeding the tool in too fast, taking too heavy of a cut with the reamer, or poor coolant flow not removing the chips fast enough or any combination of the above. Could also happen if you chucked a metal cleaning rod up in a hand drill and went to town on the chamber. I'm assuming you didn't do that. What does your brass look like after it's been extracted? Dents, scratches, or any other suspect marks?

IMHO, I would try exchanging that barrel. If that's not an option, have a gunsmith check it out to see if it can be rechambered or polished out enough to solve feed issues, otherwise that barrel is scrap.

 

[AznTactical]

To add to @Supersubes' post. Gaulding, happens with dull/chipped reamers, or metal shavings getting caught in between the reamer and barrel by either feeding the tool in too fast, taking too heavy of a cut with the reamer, or poor coolant flow not removing the chips fast enough or any combination of the above. Could also happen if you chucked a metal cleaning rod up in a hand drill and went to town on the chamber. I'm assuming you didn't do that. What does your brass look like after it's been extracted? Dents, scratches, or any other suspect marks?

no hand drill used....yet. Soaking the chamber in BoreTech C4, check tomorrow. On live rounds that failed to chamber or get a light strike there is witness marks. No witness marks on the rounds that successfully went off.

 

[AznTactical]

Ooof.... what specific ammo ? Subs? supers ?

Hornady 190gr subs factory.
Ammo Inc Stealth subs factory.
AAC 208gr subs factory.
Federal power shock 150gr supers factory.
220gr Nosler sub handloads.
110 Barnes TacTx super handloads.
All factory ammo performed about the same in success rate. No ammo was better than the other. My handloads had a better chance of success.

 

[bfoosh006]

Please let us know your extra cleaning results, or if Odin replaces the barrel.

 

[AznTactical]

Please let us know your extra cleaning results, or if Odin replaces the barrel.

Ran a Ø0.40 nylon brush saturated in BoreTech C4 on a hand drill in the chamber for 40-60 seconds total, cleaned it out and ran bore scope. Same thing. Going to borrow some Go and No-Go gauges to check headspace before contacting the manufacturer this week. Was going to use a copper brush but going to skip that. Thanks all.

 

[MontanaMan]

Tool chatter; not going to polish that out.

MM