Bluing Mystery

[doubleDarms]

I'm just begining to learn how to blue firearms and have been doing fairly well until today. I received an older Mosberg 12 gauge rifled shotgun barrel to re-blue. I bead blasted and sanded it as always, degreased etc. Then droped it in the bluing tank at 290 just like always and went about my business. After like 3 minutes I went over to stir and swirl and upon pulling the barrel up to slosh it around it was still completely unblued except for the area right aroung the chamber. I just stirred and dropped it back in and shrugged it off thinkin well huh ?? After like 3 more minutes or so I went back and still nothing. The area around the chamber had a perfect line right at the end of the chamber that was fully blued, but the entire rest of barrel was still completely unaffected. So what gives ?

 

[Preacher]

Did you use glass beads ???
Other than that it's probably a steel problem in that barrel.......

 

[shot410]

Stainless barrel?

 

[doubleDarms]

No I should have said sand blasted, I used regular fine sand. And the barrel is definitely not stainless ! A magnet sticks to it, and from outward appearance there's no difference between the chamber area and the rest of barrel. The barrel is probably early 90's manufacture. I'd post a picture of it but I already painted it with gunkote. But there was a perfectly circular line about 3" up from breech end basically containing the chamber area that blued perfectly, the rest of the barrel was as if it had never even been in the tank. Not even a light discoloration or nothing. The origional finish I'd swear was some type of bluing.

I've since re-blued 4 AK magazines and they came out perfect. I would think that there has to be something in the barrel steel itself to make that perfectly circular line, almost like it has a chrome-moly chamber and some other type of steel for the barrel. But there's no detectable line there on the barrel/ chamber junction other than where the bluing stopped.

 

[blawton]

Be careful thinking that all stainless is not magnetic, some types are. I really dont think the glass beads would have anything to do with it but i would recommend switching to granite or aluminum oxide. After looking at everything you have said i would have to say you found a stainless barrel on that thing. You can also blue stainless as well. If you need any help i can get you in contact with someone that can help you out. Send me a PM if you would like.

bobby

 

[Robert]

I'm just begining to learn how to blue firearms and have been doing fairly well until today. I received an older Mosberg 12 gauge rifled shotgun barrel to re-blue. I bead blasted and sanded it as always, degreased etc. Then droped it in the bluing tank at 290 just like always and went about my business. After like 3 minutes I went over to stir and swirl and upon pulling the barrel up to slosh it around it was still completely unblued except for the area right aroung the chamber. I just stirred and dropped it back in and shrugged it off thinkin well huh ?? After like 3 more minutes or so I went back and still nothing. The area around the chamber had a perfect line right at the end of the chamber that was fully blued, but the entire rest of barrel was still completely unaffected. So what gives ?

doubleDarms,
I do not know the Mossberg shotguns, but, from what you notice, the barrel itself culd well be press- fitted on a sleeve bearing either the lugs or the hinge in the case of a breech-open single or double shotgun.

In this case, it is entirely possible that the barrel, a simple tube, has been chrome plated (parachromed), and it is the reason why blueing does not bite on it.
R.G.C

 

[blawton]

That would make complete sense what robert is thinking.

 

[Robert]

That would make complete sense what robert is thinking.

Bobby,

And, if he really want to blue it, he will have to remove the plating...but, imbedded as it is now by the sand blasting, I would not recommend to do this, as the result of polishing could not be guaranteed, and there is a limit on a shotgun barrel thickness...

Cerakote, maybe??...

R.G.C.

 

[blawton]

Yes that duracote or powder coat may be the only options. Anyway you look at it if its plated its not going to work extremely well but should get the job done. Might want to go over it with some alum oxide media and hope for the best.