Green residue on bolt.

[5pins]

Dissembled my rifle today, after taking it shooting yesterday, and found green residue on the tail of the bolt. I have never seen this before. I put about three hundred rounds through it, a mix of factory and handloads. The color makes me think it’s maybe some kind of copper corrosion.

http://generalcartridge.net/images/PICT3875.JPG

[ALCOAR]

I would not go so far as to say "corrosion", but you are prob. right in the fact that its a bit of copper fouling mixed with whatever particular bore or gun cleaner you happened to be using.

It should clean up real easy with some clp and a small wire brush and its not a problem as long as you remove it and just dont let stuff like that sit on parts for to long.

eta.....sometimes salt in the air, etc. can cause that type of discoloration but spokane isnt exactly beach front...;)

[Iraqgunz]

Looks like residue from using some type of cleaner. Probably is a good idea to do a good wipe down when you are done cleaning and then apply some light lubrication.

[Quib]

Fairly common occurrence, usually found on the gas tube as a thick gooey green substance. As mentioned, simply a reaction to copper and residual solvent. That bolt looks very dry though. A wipe down with CLP for storage sure wouldn’t hurt.

[markm]

The other time I've seen green that bad was in the blast chamber of a YHM phantom can where the shooter ran Wolf through it.

[Blankwaffe]

Another little tip.When your done shooting for the day,pull the BCG back out of battery(about 1/2") using the charging handle and hold it in place,then put a few drops of oil or CLP in the gas ports on the side of the carrier and work the action a few times to spread it.
As a note the Break Free CLP aerosol works perfectly for this and about the only use I have for the aerosol CLP.
Simply install the little red tube that comes with the can of CLP on the spray nozzle,pull the BCG back as mentioned and insert the application tube into one of the gas vents and give it a shot.Remove the application tube from the carrier vent and release the BCG,then work the action a couple times to spread the CLP.
The Break Free CLP aerosol will foam up and thoroughly coat the bolt tail,gas rings and the inside of the carrier.Not only does it help protect from corrosion if PM is delayed,but the solvent content is higher in the aerosol CLP and effectively softens the carbon collected on the parts for easy removal when you do PM the weapon..
HTH

ETA
I also do this during extended use,high round count days, when I take a break in firing.I also like to relube the entire BCG every 300-400 rounds when possible.
I do PM as soon as possible after firing,and before I do anything else...golden rule is "the sun never sets on a dirty weapon" and I live by it,even if its nothing but a simple wipe down of the parts with a oiled cloth.Its how I was raised/taught and I follow it.Works too.

[Quib]

From the position of that spot, it wouldn’t surprise me if the gas tube has some residue in it as well.

If the upper receiver is cleaned inverted, solvent can migrate down into the gas tube. During storage, this residual solvent slowly runs down the gas tube dissolving firing residue along the way

Gravity pulls it down through the gas tube, into the gas key, and finally onto the bolt tail.

This is one reason why I hit the gas tube with a quick shot of either brake cleaner or Break-Free Powder Blast, I cover this in my cleaning tutorial which can be found here:

http://m4carbine.net/showthread.php?t=35490

[rgaper]

Be careful - could be Predator blood...

Just take some fine grit sandpaper to it and it'll come right off along with the carbon & grime. Keep an eye on the gas tube to see if you have the same stuff there.

[5pins]

It came off easily enough with just normal cleaning. More then likely just a reaction with the Hoppies I use when I clean, but I have never seen this before. There was some in the carrier also so I went and put the bolt and carrier in my ultra sonic cleaner after my normal cleaning.

I’m going to flush out the gas tube with some brake cleaner. I normally do it at around the 1000rd mark anyway.

This was the first time out with this build so maybe there was something in the gas tube that the manufacture put in it for storage.

[boltcatch]

The other time I've seen green that bad was in the blast chamber of a YHM phantom can where the shooter ran Wolf through it.

Pretty much any can will turn green like that in the blast chamber if you let it sit long enough.

[Blankwaffe]

It came off easily enough with just normal cleaning. More then likely just a reaction with the Hoppies I use when I clean, but I have never seen this before. There was some in the carrier also so I went and put the bolt and carrier in my ultra sonic cleaner after my normal cleaning.

I’m going to flush out the gas tube with some brake cleaner. I normally do it at around the 1000rd mark anyway.

This was the first time out with this build so maybe there was something in the gas tube that the manufacture put in it for storage.

Yeap,Ive never seen any fouling that looks like that either.I use a metric ton of Hoppe's No.9 Nitro solvent,to include as a dunkit solution(following Quibs old technique).I use BoreTech Benchrest blend for heavy fouling.Ive not seen this in that regard either.
That said Ive never hosed the gas tubes out.
Guess it could have been some lube or grease of some sort the manufacturer uses that got blown in and burnt.But generally speaking my bolts look fuzzy and black on the tail after a few hundred rounds.

[markm]

Pretty much any can will turn green like that in the blast chamber if you let it sit long enough.

I don't think my can has ever done so. :confused:

But I have seen a little green action on plain old A2 flash hiders that have never had a can mounted on them. Must have something to do with the vaporized copper deposits.

[Plumber237]

Excuse the necro post, but I was cleaning my rifle today and found this odd bluish corrosion stuff on the bolt tail and a little inside the carrier. It looked like the corrosion you see on old batteries. So I came on here figuring that somebody had seen this before. Anyway, I doused it with Hoppe's and wiped off what I could, all the blue discolor stuff came off after a little bit, but I'm wondering if I should try to get all the carbon off that was underneath it just in case (spread corrosion?). I know that having carbon build up on the bolt is normal and self limiting, but I'm concerned about this corrosion type crud. Any thoughts?

[thopkins22]

Excuse the necro post, but I was cleaning my rifle today and found this odd bluish corrosion stuff on the bolt tail and a little inside the carrier. It looked like the corrosion you see on old batteries. So I came on here figuring that somebody had seen this before. Anyway, I doused it with Hoppe's and wiped off what I could, all the blue discolor stuff came off after a little bit, but I'm wondering if I should try to get all the carbon off that was underneath it just in case (spread corrosion?). I know that having carbon build up on the bolt is normal and self limiting, but I'm concerned about this corrosion type crud. Any thoughts?

As was mentioned, it's corroded copper. Copper from the bullet is vaporized and most of it welds to the bore. Occasionally some of it starts to find itself on flash hiders and even being blasted back through the gas tube finding your bolt tail. A little moisture, and there you have it. Not a big deal...but there's no harm in cleaning it off, in fact it's probably wise as long as you follow common sense and don't screw up your gas rings.

It also could have found itself in your gas tube from when you cleaned it with copper remover. And then was blasted back. Either way, that's what you're looking at, not corrosion of the bolt itself.

[Plumber237]

Thanks for the feedback, it'd been awhile since I've cleaned my rifle, and it had only had about 500 rounds since I cleaned it last. But it sat for almost 2 weeks since my last range trip, so I was a little paranoid when I saw that weird corrosion today. I'm just glad it's not a big deal, and I'll be making sure that I atleast wipe the bolt down after shooting each range trip so that crud doesn't have time to sit.

[Plumber237]

Another little tip.When your done shooting for the day,pull the BCG back out of battery(about 1/2") using the charging handle and hold it in place,then put a few drops of oil or CLP in the gas ports on the side of the carrier and work the action a few times to spread it.
As a note the Break Free CLP aerosol works perfectly for this and about the only use I have for the aerosol CLP.
Simply install the little red tube that comes with the can of CLP on the spray nozzle,pull the BCG back as mentioned and insert the application tube into one of the gas vents and give it a shot.Remove the application tube from the carrier vent and release the BCG,then work the action a couple times to spread the CLP.
The Break Free CLP aerosol will foam up and thoroughly coat the bolt tail,gas rings and the inside of the carrier.Not only does it help protect from corrosion if PM is delayed,but the solvent content is higher in the aerosol CLP and effectively softens the carbon collected on the parts for easy removal when you do PM the weapon..
HTH

Thanks for the tip Blankwaffe, I've done this the last few range trips at the end of shooting and no more corrosion crap. Although I have been more careful with wiping the Hoppe's off good before applying my lube, but either way I'm guessing that will be the last time I get that blue/green crud.