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matt86
08-09-15, 02:38
I just finished my first 300 build and after firing one box of Varmmageddon 110 gr rounds, I found this. The rifle has a Ballistic Advantage 8" bbl with pistol gas. Thoughts?
http://i1096.photobucket.com/albums/g322/mattnewman/Mobile%20Uploads/IMG_20150808_223048366_zpstlk3ipfy.jpg (http://s1096.photobucket.com/user/mattnewman/media/Mobile%20Uploads/IMG_20150808_223048366_zpstlk3ipfy.jpg.html)
http://i1096.photobucket.com/albums/g322/mattnewman/Mobile%20Uploads/IMG_20150808_223109295_zps3ozrbvwp.jpg (http://s1096.photobucket.com/user/mattnewman/media/Mobile%20Uploads/IMG_20150808_223109295_zps3ozrbvwp.jpg.html)
tom12.7
08-09-15, 06:57
Best bet would be to contact the manufacturer first. Usually, this fades away pretty quickly in a new barrel when you push more rounds through it.
lysander
08-10-15, 07:00
You do know that the AR-15/M16 gas system blows barrel gas back into the bolt carrier and receiver?
bp7178
08-10-15, 19:19
Do you have any more details about the ammo?

Is it some type of copper deposit? Try cleaning it with a copper remove or ammonia to see if it turns blue.
matt86
08-11-15, 21:46
You do know that the AR-15/M16 gas system blows barrel gas back into the bolt carrier and receiver?

I didn't know that! I was wondering what that weird tube was when I built the gun! Thanks!
Rolls-Royce
08-15-15, 00:33
Looks like copper from jacketed bullets. I recently built a second 300 BLK upper using a brand-new CMMG barrel and its first range trip was last week. My bolt's tail had deposits like yours, and MPro copper solvent took it nearly completely off. However, I didn't have any deposits on the charging handle.
tom12.7
08-15-15, 16:41
Some nitrided barrels that do this severely can even plug the gas port in some instances. If it goes away, fine. If it doesn't, contact the manufacturer. This may, or may not be an issue.
Rolls-Royce
08-15-15, 19:55
Some nitrided barrels that do this severely can even plug the gas port in some instances. If it goes away, fine. If it doesn't, contact the manufacturer. This may, or may not be an issue.
Not contradicting you at all, Tom, but why nitrided barrels in particular (yep, mine's nitrided)?
tom12.7
08-15-15, 20:22
A deviation into the bore can have longer term consequences in a harder barrels than a softer ones. Nitrided barrels are hard. Other aren't so much. A defect that can displace copper at a rapid rate can be attributed to many things may be due to many things. I would take a serious consideration looking around the bore around at the gas port.
Rolls-Royce
08-16-15, 21:12
Got it. Thanks!