Help!! Experts I have Excessive copper on the sides of 300 Blackout Bolt

[2clicks]

Tried out my new Blackout yesterday after 20 rounds I went to clean the bolt carrier group & the bolt had a bunch of copper particles stuck to the sides in the widest area where bolt rides/slides inside the carrier group restricting its back and forth movement. Also on the very end where the firing pin enters the bolt there were the same particles of copper they were stuck I would say the heat got them stuck to the surface big time. Any ideas on the cause of this? I was using 178 Amaxes and 150 SST Hornady bullets. I'm not quite sure what would cause copper to be blown back into the bolt like that other than the feed ramps or the gas hole in the Barrel itself possibly shaving off copper and pushing it back into the bolt carrier group. Just wondering if anybody has experienced this and what was their remedy to clear it up? Thanks

 

[Delta4-3]

Tried out my new Blackout yesterday after 20 rounds I went to clean the bolt carrier group & the bolt had a bunch of copper particles stuck to it in the widest area where bolt where rides inside about carrier group restricting its movement. Any ideas on the cause of this? I was using 178 Amaxes and 150 SST Hornady bullets. I'm not quite sure what would cause copper to be blown back into the bolt like that other than the feed ramps or the gas hole in the Barrel itself possibly shaving off copper and pushing it back into the bolt. Just wondering if anybody has experienced this and what was their remedy to clear it up? Thanks

Are you running a can?

 

[LRRPF52]

What makes you say it's copper and not brass? Sharp extractors are the #1 cause of brass shavings.

If you are seeing actual copper shavings in the bolt face, then we would need more details, namely pics.

 

[2clicks]

The majority of the accumulation was on the inside of the bolt carrier and the issue is that the majority of the build up right here on the ridge was restricting the function of the bolt from sliding in and out of the bolt carrier group easily.

 

[LRRPF52]

If you have some copper solvent, take a cue tip and just a dab of solvent, and see if that material turns green, then clean it off.

Brass just gets dull, grayish-brown when it oxidizes, so you should be able to determine the element of this material.

 

[2clicks]

With out a doubt it's copper. if you look real close to the right side of the bolt you can actually see some of the specks on the top portion of it where the gas tube goes inside the bolt. Odd thing is the bolt face and locking lugs have no copper on them and only minimal traces of brass. I'm not concerned about how to get it off. I'm wondering why the heck it's there, and how the hell did it get in the back of the bolt and inside the bolt carrier group? I've never seen copper in these places before in any of my Ar's and I've been fooling with these things since 1989. Just not in the blackout chambering until recently.

 

[LRRPF52]

Are you chamfering the inside of your necks before you seat the bullets? I've seen issues where I've let an unchamfered neck slip through during brass prep, and the jacket ends up getting sheared a bit during bullet seating.

Copper jacket pieces could get blown back in the action from this type of scenario. I only mentioned the solvent to determine that it is in fact copper, and not brass, not for cleaning purposes.

 

[2clicks]

Yes I chamfered the brass inside and out. I even annealed the brass on my Giraud annealing machine. If you look at the area the build up was on its directly below the area where the gas blows into the carrier, I think the copper is blowing onto the bolt from the gas system somehow. I'd like someone that has experienced this situation to let me know what their fix was and what caused it. I kind of doubt it has a bad gas hole in the barrel (bur from drilling the hole) but this but it's my only suspicion.

 

[tipper]

It get there the same way it gets laid down in the barrel from the hot gases

 

[MSTN]

What type upper?

Do you have a borescope? Have you been waiting for the right excuse to buy one? This could be it!

 

[rideHPD]

What do your boltface and spent casings look like? My bolt rapes my brass (pretty sure it's just overgassed, need an adj gb) and the shavings make their way to the back of the bolt and oxidize leaving a green patina on the bolt tail and on the inside of the carrier. Could be overgassing, could be sharp extractors as LRRP said. It's not from hot gasses.

 

[tipper]

What type upper?

Do you have a borescope? Have you been waiting for the right excuse to buy one? This could be it!

Tis will just make you ask more questions

 

[MSTN]

Tis will just make you ask more questions

Having a borescope is indeed a mixed blessing.

 

[2clicks]

COPPER, COPPER, COPPER I DON'T HAVE A BRASS ISSUE... My spent brass looks great no shavings scratches or deformities ejector swipes nothing wrong with the brass whatsoever anywhere including the part where the ejector latches on to the bottom of the brass. My upper is a Bushmaster upper from a varminter that had about 150 rounds fired through it before it was turned into the blackout. Thanks guys I guess I'm going to stone my feed ramps a bit and load individual rounds manually to see what happens next time. As it is I cycled 10 rounds or so without firing them with only minimal traces of copper on the feed ramps and I think the copper that is getting on the ramps is from dragging the bullet back across the ramps before being ejected again. Maybe it is time for a bore scope...

 

[arnie19]

I wonder if the gas hole in your barrel has a burr that is shaving your bullets and blowing in to your gas tube and back to the BCG.

 

[2clicks]

Arnie19 that's what I'm thinking but I don't know for sure yet I was hoping someone might be able to say yeah Man without a doubt that's what happens when there's a burr at the gas hole in the barrel. I called the MFG of the barrel and I seem to be more qualified than him. It seems to be the only logical explanation to me how the hell would copper only be on that part of the bolt in such thickness to impede it's mechanical function inside the carrier bolt face and lugs were clean. I guess I'll have to call GAP Or Frank White. I hate to bother those guys they have bigger fish to fry.

 

[2clicks]

Wow my google fu is weak I finally found a thread on a search that described the exact same situation I'm having. The culprit Was a burr in a brand New large caliber AR barrel, same scenario as mine. It described the welding of copper "shards" to the bolt from the hot gases blowing the copper onto the bolt from the gas tube. They said it would cease once the burr was shot out. HAHA that's funny I guess there might be something to breaking in barrels after all. I gave up on that idea years ago. I'll post a follow up here after my next range session to let you all know if it finally got "broke in" or not.