theprof1
(.224 member)
19/07/19 06:55 PM
Pitted chambers - a possible solution ?

Warning, this is a silly idea of mine so please feel free to call me a dangerous nutter.
Some years ago I had a .500 3" BP Jeffery double, the right barrel had a noticeable pit about half way down the chamber at about 2 o'clock viewed from the breech. I tolerated this for the life of the rifle while I was it's custodian. When a load seemed to get close to maximum the brass would acquire a small raised dimple at the pit location, I then backed off in my regulation loads. I have often wondered if a good clean of the pit, with Hydrochloric acid - which I used to use for stripping old barrel browning when it had gone beyond cleaning up and needed re browning.
My thought was a small deposit of dental amalgam ( mix of mercury, silver, tin and copper). This stuff is tough takes years of gnawing bones to break up fillings. I would be softer than the chamber steel so over filling could be honed / lapped out with little effect on the steel. It would be incompressible and hard. There may be more effective ways of rescuing a chamber in which extraction becomes difficult, but I have been out of gunsmithing for years. Amalgam doesnt seem very popular these days as there are many more painless dental filling materials these days, perhaps it may not even be used any more but some old near retired dentist may be persuaded to dust of his amalgamating equipment and try it on a pit?
All comments welcome.


tinker
(.416 member)
19/07/19 11:38 PM
Re: Pitted chambers - a possible solution ?

It doesn't sound like a silly idea to me at all.
Sounds like it would work.

I don't know the specifics on the alloy for dental amalgam. It's time I look at the specifics.
The compression strength is in the range of 55,000 - 59,500 pounds-force per square inch
Interesting proposition!


theprof1
(.224 member)
20/07/19 12:05 AM
Re: Pitted chambers - a possible solution ?

Thank you for having the interest to reply. The main issue is adhesion of the amalgam to the parent steel. This would be overcome by a thorough cleaning of the pit. My procedure would be as follows : get a pack of brake clean, use the wife's hair dryer and carefully put a right angle bend on the tip of the tube, blast the pit - this will remove most of the grease, oil, crud, and powder/ smoke residue. I would do this twice as it evaporates quite quickly. Then you would use a fairly concentrated solution of caustic soda - Na Oh. Beware this shit requires full P.P.E - safety glasses and rubber gloves, one drop of Caustic in your eye will crater the surface of the eye ball.... This process of using caustic is called scouring the steel. Removes all built up oils, waxes and carbonaceous material. After using the caustic - 20 mins, flush with a full jug of boiling water, this will remove remaining caustic and heat the chambers so they dry out. The next step is to use a cotton bud soaked in strong hydrochloric acid, this will remove some or all rust remaining in the pitting - again flush well with boiling water. By now you will have 2 things, a clean pit and a chamber avid for oxygen, it will start to rust real quick, just with atmospheric oxygen. The steel will be naked and oxygen hungry. You need to perform the last step just before your trip to the dentist. Hopefully your dentist will allow for your slightly deranged request and book it down as a standard tooth filling so you can claim it on your health insurance. Best of luck lol.

DarylS
(.700 member)
20/07/19 12:19 AM
Re: Pitted chambers - a possible solution ?

VERY interesting topic. I am quite interested in the results of this experiment.

theprof1
(.224 member)
20/07/19 12:26 AM
Re: Pitted chambers - a possible solution ?

Sadly Tinker and Daryl, I am not any longer in possession of the 500, had to pass it on to to it's next custodian The thought was there, just hoping to give some hope to those with damaged chambers in their valuable guns. This is a small thought for the next generations, lucky enough to own a fine antique rifle.

Vladymere
(.300 member)
20/07/19 07:53 AM
Re: Pitted chambers - a possible solution ?

Currently my dentist uses an epoxy mixture, that is cured by a black light, for fillings. I wonder if a good epoxy might not work for filling pits in the chamber?

Vlad


tinker
(.416 member)
20/07/19 08:02 AM
Re: Pitted chambers - a possible solution ?

The fellows at the shop are interested.
I'll be getting some materials and going forward with this.

For shotgun, bore rifle, and BPE chambers - and many NE chambers, this should be a good solution.
I don't know why I hadn't ever thought of this.
I and many other guys I know have thought of the epoxy materials, but one way or the other we've all steered clear of the plastic fantastic.

I'll post back with whatever I learn.
I will be talking to my dentist too along the way.
I'm sure he'll have some good points to consider.


theprof1
(.224 member)
20/07/19 09:22 AM
Re: Pitted chambers - a possible solution ?

Great keep us posted on your trials Tinker.

BillG500
(.300 member)
20/07/19 12:25 PM
Re: Pitted chambers - a possible solution ?

Why at all bother? If it does not affect shooting etc then there really is no need to mess with it. I think there are much better products out there that would work better than dentist goo if you really had to play with it. I'd be buggered if I'd let some hick gunsmith put dentist goo in my double rifle barrels, but you can experiment on yours for sure

tinker
(.416 member)
20/07/19 12:51 PM
Re: Pitted chambers - a possible solution ?

Quote:

Why at all bother? If it does not affect shooting etc then there really is no need to mess with it. I think there are much better products out there that would work better than dentist goo if you really had to play with it. I'd be buggered if I'd let some hick gunsmith put dentist goo in my double rifle barrels, but you can experiment on yours for sure




Thanks for your consent!


BillG500
(.300 member)
20/07/19 02:50 PM
Re: Pitted chambers - a possible solution ?

Your welcome Tinker, anytime.

I look forward to the results of your experiments with dentists goo in rifle barrels with great humor


DarylS
(.700 member)
20/07/19 03:07 PM
Re: Pitted chambers - a possible solution ?

Quote:

Why at all bother? If it does not affect shooting etc then there really is no need to mess with it. I think there are much better products out there that would work better than dentist goo if you really had to play with it. I'd be buggered if I'd let some hick gunsmith put dentist goo in my double rifle barrels, but you can experiment on yours for sure




I might be wrong.- The Lord knows I've been wrong many times before, but I don't think you've grasped the 'jist' of this fix.
The boys are talking about taking a gun that is virtually unshootable due to chamber pits, and returning it to full function.
As far as I know, aside from re-chambering to a larger, perhaps necked case, this to day has been impossible.

To a functioning rifle, no, but to a gun not shootable due to chamber pits, I'd say, lets experiment.


tinker
(.416 member)
20/07/19 03:41 PM
Re: Pitted chambers - a possible solution ?

Quote:

...I don't think you've grasped the 'jist' of this fix...




I think you are seeing clearly, Daryl.
There is a great deal of difference between his fantasy goo and metal amalgam.
And that's fine.

And yes Daryl, we are discussing the restoration of function to a gun or rifle (within operating pressure limitations) with metal amalgam.

There are other ways to accomplish this.
Micro-welding is one way to do it. There are actually machines that can get in there and do the work with minimal-to none at all heat affected zone. The process is expensive and not for all applications.
Another way to go is to braze the affected area and re-cut the chamber - this way has greater heat affected zone.
Another way is to sleeve the chambers. This method can work, and some gunbuilders will do it. There have been discussions of catastrophic failures from this method, here (years ago) and on other double rifle sites.
Also there's the re-barreling approach, which is tremendously costly, and with a Damascus gun you can basically forget about finding Damascus replacement tubes.

There's also been the Teague sleeving process which essentially leaves the outer skin if the original tubes intact and full length sleeves are bonded in place.
I haven't heard anything of this process in the last few years. I wonder if the patent process is still available.

Mercury amalgam is basically a metal inlay process.
The resulting inlay is very tough with excellent compressive strength. This process, if it's actually viable (I'm willing to give it a test drive) is a cold process that doesn't require refinish to the barrels and won't affect regulation of a gun or rifle.
I know it's not fantasy goo.
It's ok with me if our friend here wants to maintain his position. More power to him.



Cheers
Tinker


Huvius
(.416 member)
21/07/19 04:20 AM
Re: Pitted chambers - a possible solution ?

When I was a kid, my uncle had a number of old doubles and if they had pits, he would fill them with clear nail polish.
They would hold up for a session or two before dislodging.
Then, clean the chamber with remover and fill them again.
I never watched him do it so I'm not sure if he used a waxed case to smooth the polish or what.

I have wondered if a nickasil plating would work.
Hard as hell and can only be polished with diamond I think.
It's used for replating two stroke cylinders mostly as far as I know.


tinker
(.416 member)
21/07/19 05:04 AM
Re: Pitted chambers - a possible solution ?

Quote:

wondered if a nickasil plating would work.
Hard as hell and can only be polished with diamond I think.
It's used for replating two stroke cylinders mostly as far as I know.




I know that plating has been used to remedy wear at the hook and at the bites. I haven't heard of it being used in chambers, but it's possible. Masking of everything but the pits would allow selective application, as is done at hooks and bites - but it's so much harder than the parent material.


The nail polish remedy is an interesting solution.
Definitely beats re-barreling the gun.


BillG500
(.300 member)
21/07/19 07:50 AM
Re: Pitted chambers - a possible solution ?

Go for your life guys, I'm not trying to start a shit fight, but just laughing at what you are trying to use. go to any good gunsmith and ask them that you want to use dentist amalgam (goo) or better still ask him to do it for you and see what his reply is. Seriously guy's it's so silly it's laughable. I do get the gist Daryl, if only you read my original reply,

"If it does not affect shooting etc then there really is no need to mess with it"


In the very first line of the this post the original poster said:

"Warning, this is a silly idea of mine so please feel free to call me a dangerous nutter."

Well I'm calling it guys.


Sure there are possibly other ways to do I'm just having a laugh at the original idea. I don't know why you are so defensive. I'm just having a laugh. Take a pill sit back and relax.


93x64mm
(.416 member)
21/07/19 08:37 AM
Re: Pitted chambers - a possible solution ?

It regards to joining a double rifle a (High force?) solder is used to perform this task, admittedly this will be difficult to solder inside a barrel; but with an extremely hot piece of iron made to deliver the heat to correct area you should be able to then fill the void (after cleaning & prepping) like the old separate heat sourced soldering irons.
To redo the chamber after a small dab is put on again will be a tense moment, but if set up right & taken very slow with a finishing reamer - I believe doable!
I am no metal smith, so I'm only throwing suggestions out there to far more knowledgeable folks!
To repair an old rifle back to shooting condition certainly is a big ask, but if it was say your great grandfather's & it had history & real semimetal value to you....wouldn't you try to get it going again?


tinker
(.416 member)
21/07/19 09:10 AM
Re: Pitted chambers - a possible solution ?

Quote:

It regards to joining a double rifle a (High force?) solder is used to perform this task...





High Force 44 is only good for 38Kpsi.
Also the amalgam is a cold process.
Mercury is some amazing stuff. Science.


tinker
(.416 member)
21/07/19 09:18 AM
Re: Pitted chambers - a possible solution ?

Quote:

amalgam (goo)




The proposal is interesting.
The material is *all metal* and as applied has fantastic compressive strength.

My first impression was something like yours but the proposition has merit.
It's actually worth a try.

This discussion isn't about "something someone is trying to do" rather it's a discussion of "something that could actually be a good solution"

But goo.
Really, my guy.
Goo.
55Kpsi metal goo...
Your reaction is pretty entertaining.


Postman
(.375 member)
21/07/19 11:20 AM
Re: Pitted chambers - a possible solution ?

Before filling with amalgam, would you first perform a root canal procedure? MUST remove the rot before attempting to fill. Not certain amalgam will stick properly. If it does, well why the hell not??? Maybe the black light epoxy would be more effective? If you can’t recut the chamber to a larger cased round of same caliber as would be one of the traditional and sometimes viable fixes and the rifle is otherwise effectively useless in it’s present form, well just maybe the concept has merit.

Remember, many wonderful ideas in this world started with an idea most thought was lunacy..... Hell, many thought the moon was made of cheese before we landed people up there!!!!!!!!!


tinker
(.416 member)
21/07/19 11:31 AM
Re: Pitted chambers - a possible solution ?

Quote:

Before filling with amalgam, would you first perform a root canal procedure? ... Hell, many thought the moon was made of cheese before we landed people up there!!!!!!!!!




I'm sure it needs to be free of rust and debris, likely needs a bit of undercut too.

On that cheese VS rock business, there are plenty of fellows who don't believe that we ever got there, and many who don't believe our planet is shaped like a sphere.
We might have some of the flat-planet wizards among us here on the site!


eagle27
(.400 member)
21/07/19 12:39 PM
Re: Pitted chambers - a possible solution ?

Amalgam, solder!!!!! there's newer better products that will do the job. I've used Loctite liquid metal in various applications in conjunction with Loctite cleaner and prep. There's a couple of different liquid metal products, the two tube epoxy liquid metal the one I have used. The colour is grey so will more or less match the chamber colour.

Once the pit is filled and hardened, a piece of dowel with a wrap of fine wet and dry paper will smooth out the filled pit.


theprof1
(.224 member)
21/07/19 12:44 PM
Re: Pitted chambers - a possible solution ?

I was hoping the rust would be removed with the hydrochloric acid leaving a fairly sharp surface profile for the amalgam to get a grip on. there may be better more efficient chemicals than HCL though, I would avoid those converters that leave a smooth shiny deposit behind..

tinker
(.416 member)
21/07/19 01:36 PM
Re: Pitted chambers - a possible solution ?

I'm sure it depends on the pitting.
I might just cut a somewhat dovetailed channel and do some inlay. Have a look, so to speak.


DarylS
(.700 member)
21/07/19 03:48 PM
Re: Pitted chambers - a possible solution ?

I was also thinking of an undercut to hold it in place.
The pits might be pits as caused by a corrosive, as in primer or in the powder itself.
If so, the pits might just be undercut already, like chlorate and perclorate fouling does to some steels, rather than simple dished-shaped pits caused by normal rust/oxidation.
Either way, they must be thoroughly cleaned. In the chlorate damage, there might already be the fill-holding undercut.
Getting a good look with a Hawkeye bore scope should show the nature of the pits.


Postman
(.375 member)
21/07/19 10:29 PM
Re: Pitted chambers - a possible solution ?

I’m thinking the steel epoxy and similar products are maybe the better way. In any event, if it’s pitted, I don’t see how any of these “solutions” would be effective other than for a very short period of time until it crumbles, peels off, etc. I honestly don’t know how one might semi permanently repair the pits without cutting or molten metal being involved. I’m just about the last person to ask when it comes to metallurgy and/or repairs thereof.

DarylS
(.700 member)
22/07/19 01:24 AM
Re: Pitted chambers - a possible solution ?

I'm concerned with epoxies, there may be some crushing or pulverizing from the pressure of full loads.
I still think the amalgam sounds feasible, or at least the most interesting.
Once set, it is very hard & dense.


DoubleD
(.400 member)
22/07/19 09:32 AM
Re: Pitted chambers - a possible solution ?

The old school method is to sleeve the chamber.

The new school method is clean the pits with alcohol apply devcon steel or the MILSURP favorite JB Weld.

Both are frequently used for thAt purpose. Devcon and believe JB also, can be machined when set. After applying ream an polish.

I have pitted .303 Martini chamber to fix this way.


Devcon is amalgam of epoxy and powered steel.

Remember the pressures we talking about are per square inch. The pits are most measurable in.001's of a square inch. As a well a thickness measured in that same miniscule thickness.

What is the actual pressure on say.010 sqin. in a gun developing 18 ton psi.


DarylS
(.700 member)
22/07/19 01:24 PM
Re: Pitted chambers - a possible solution ?

Understand your point.

tinker
(.416 member)
22/07/19 03:35 PM
Re: Pitted chambers - a possible solution ?

Quote:


Devcon is amalgam of epoxy and powered steel.





In that respect, a bowl of cereal is an amalgam.

But I see where you are with the Devcon.
I've used pounds of that material in the industrial setting. I've machined and ground and threaded and textured the stuff many many times on many different kinds of equipment.

It's great stuff. Like anything it has it's strengths and it's weaknesses - and for lighter pitting I can see why a fellow would use it as it has great tooth on most metals. I've used it as bedding on heavy recoiling big bore rifles with great success.


DarylS
(.700 member)
23/07/19 01:41 AM
Re: Pitted chambers - a possible solution ?

Years ago, I used Devcon plastic steel for bedding on all my rifles. After they switched to the 7/1 mix ratio from 50/50, I stopped using it. I had difficulty getting the mix right.

JB Weld works just fine for bedding on lighter recoiling rifles now. Might even work for some pitting problems.


Juglansregia
(.275 member)
23/07/19 04:45 PM
Re: Pitted chambers - a possible solution ?

I'd be concerned about the potential for Liquid Metal Embrittlment of the barrel steel.

The susceptibility of various alloys of steel to embrittlement by mercury and other liquid metals is well documented. I'd be researching it real hard before trying it, and consulting with a metallurgist familiar with firearms if in doubt. I've got no idea how mercury when part of an amalgam might affect the chances of embrittlement.


theprof1
(.224 member)
23/07/19 05:51 PM
Re: Pitted chambers - a possible solution ?

Good point, further research still needs to be done, stainless is mercury avid but whether the amount of mercury in amalgam is enough to cause any damage should be looked as various grades of iron alloys react quite differently as i understand.

Juglansregia
(.275 member)
23/07/19 07:34 PM
Re: Pitted chambers - a possible solution ?

I believe the % of mercury in dental amalgam is around 50%, by mass. Pretty high.

Even copper in the amalgam might be a possible concern, and with a combination of metals present, the influences of pressure etc, Liquid Metal Embrittlement might quickly become a complex issue in this potential application.

Another thing I've seen overlooked in gun work is hydrogen embrittlement from acid de-rusting, plating work etc where the hydrogen is not driven out by appropriate oven cycle. Pretty basic stuff but it requires some understanding of the metallurgy of the part etc. I've seen it overlooked often enough to suggest it here, might save someone some grief.


Waidmannsheil
(.400 member)
23/07/19 08:13 PM
Re: Pitted chambers - a possible solution ?

One question that needs to be asked is how deep are these pits and what size are they? If they are only very shallow and not very big in size then any mixture is going to struggle to take hold for very long. Most of these metal-putty compounds require a reasonable (relative) area and depth to get a good grip. They may hold on initially but I would suggest that after a while will fall out. Undercutting has been mentioned and this would be very helpful and would most likely make the putty stay in regardless of the size of the pit. The problem is doing the undercut. The chamber has a diameter of 0.574" (14.6mm) at the entrance to the chamber which gets smaller towards the mouth and the pits are half way along at 1.5" inches. This would make undercutting extremely difficult and at best you would only be able to access one half of the pit. Undercutting really requires you to be able to access the affected area at right angles so that you can use a very small ball nose or dovetail cutter to remove material.

Micro arc may work as you could bend the electrode into an L shape after grinding the pit to a more open shape. I have had to do this on jobs myself although on much bigger jobs. The restrictive area to work in is going to be the biggest problem.

Matt.


theprof1
(.224 member)
23/07/19 08:27 PM
Re: Pitted chambers - a possible solution ?

Hydrogen embrittlement is a factor, though more often associated with the involvement of sulphur in the reaction particularly where H2S is involved. The dental amalgam has a range of compositions with copper content in focus, from 0% copper to the higher percentages in standard mixes all giving different strengths and durability. These comments are great as it all works toward a possible easy solution or the discarding of a bad idea.

tinker
(.416 member)
23/07/19 11:23 PM
Re: Pitted chambers - a possible solution ?

Great points for study!

Chavez
(.224 member)
24/08/19 04:15 AM
Re: Pitted chambers - a possible solution ?

You might want to try a product called all metal , it’s used in auto body work but I have used it to fill pits in firearms before blueing have to mix in clean metal shavings, it also can be used as a stock bedding , I use car wax as a release agent ,

tinker
(.416 member)
24/08/19 11:07 AM
Re: Pitted chambers - a possible solution ?

The amalgam idea sounded interesting until we got to the liquid metal embrittlement issue.
I've followed up on the topic and it sounds horrible - just about the worst-case solution for pitted chambers.

The numerous high-tech epoxy and polymer products all have interesting merits. I have a huge textbook in my library, The Handbook of Adhesives and Sealants

https://www.amazon.com/Handbook-Adhesives-Sealants-McGraw-Hill-Handbooks/dp/0071479163

I tend to refer to this book when I look for such solutions

Amalgam sounded great until it didn't.



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