I have been reading with interest the discussion about barrel damage (when on the subject). I have several SxS's that are pitted to varying degrees.

I have also been looking at a number of advanced epoxy products that have been developed for industry metal repairs, most have high temperature tolerance and are machinable.

A barrel could be "super cleaned" of all rust and oils etc. by electrolysis or other means then coated with a pore filling coat of epoxy.
The tubes could then be honed straight thus leaving the pores and pits filled. I figure plastic wads will pass over the repairs without damage.

I think I will try this sometime......

Interested in hearing your results if you do give it a try. Although I'm not up on epoxy technology, I had the same thoughts a few years back, but didn't really pursue the idea to determine feasibility.

If I were to try this I would look closely at an industrial epoxy called Belzona. It is unbelievably strong and long lasting, can be machined, and is used in the repair of cracked engine blocks and many other "salvage" repairs to steel. One caveat, it's not inexpensive.

https://www.belzona.com/en/products/purpose/metal-repair.aspx

Good luck. SRH

"Expensive"?? yup- Stan, in my experiences in welding and machining ferrous metals, the best products and techniques (TIG-Plasma) always are- ?? is- is the material cost of the filler rod-flux, whatever justified by the results you desire.??

I have one basic SMAW rod I use for welding both 300 and 400 Stainless steels, also stainless to fabrication grades of mild steel, - I use Lincoln 308-16ELC in the smaller dias; and also that rod as a bare filler rod for TIG (aluminum, that's a whole 'nother ball game, isn't it.?

Now as to this filler product you mentioned as being used on cracked engine blocks- does it work on aluminum blocks with lined cylinders, as well as on cast iron blocks?? Just curious, as those differing metallurgical items may require a slightly different filler material??

Anyway, Mae and I are so glad you have bounced back from your near brush with the Grimster- Christmas best to you, Jean and all the Hillis clan down in Deep Dixie-- RWTF

Not sure about aluminum. The link to the website should take you to enough infomation to satisfy that question, but I think the answer is "yes".

Thanks for your concern, and Merry CHRISTmas from the Deep South.

SRH

Another crAzy thread...

jOe, don be ah grinch...

Most epoxy breaks down at temperatures under 300 degrees F.
Even the best high temperature epoxies break down at around 600 degrees F. These temps are considerably less than hot powder gasses, and most pitting tends to occur back where powder gasses are hottest. Even though the duration of extremely high temp is very short, I'm quite certain the combination of temperature and pressure would quickly erode your thin epoxy veneer.

There's a reason gun makers use steel to make gun barrels. You are expecting epoxy to do something it was never intended or designed to do.

Keith, I agree it's asking epoxy to do something it was never designed to do, but since no money is riding on this discussion let's pursue it a bit for kicks and giggles.

Belzona 1511 will withstand a sustained temp of up to 392 degrees Fahrenheit. Even though the flame and gases reach much higher temps, it is only for a microsecond. That's the reason it takes repeated shots in a short time to heat up the metal.

Is it possible that the epoxy would never reach 392 itself?

And, is it not also true that the heat shielding tiles are held on the space shuttle with epoxy. They get glowing red on reentry.

Is the goal to shoot or beat someone at a gun show? Turkey to treasure in one easy smear?

bill

bill,
I had not considered that aspect, good point! I just shoot'em.

To all the other comments, I suppose too much time thinking while setting feeding.

Stan, I had looked into the temperature range of Belzona, I would like to find some data pertaining to powder burn and such.
Do you happen to have NASA's phone number?

I have used Belzona on many occasions repairing blast areas of guided missile launchers. this is what we used to fill in between the ablative tiles that protect the deck and blast doors and plenums its quite a job to cut out and replace after a shot. getting the bottom of the pits clean enough to make a good bond will be challenging . The Navy uses Belzona to reline centrifugal pumps when pitting becomes a problem. good luck and I am looking forward to see your results

I have used Belzona on many occasions repairing blast areas of guided missile launchers. this is what we used to fill in between the ablative tiles that protect the deck and blast doors and plenums its quite a job to cut out and replace after a shot. getting the bottom of the pits clean enough to make a good bond will be challenging . The Navy uses Belzona to reline centrifugal pumps when pitting becomes a problem. good luck and I am looking forward to see your results

Sorry Mike. All my contacts at NASA have retired.

Stan,
Ablative tile keeps the heat from transferring to the shuttle, it glows red in one side and can be touched on the other. Yes, glued in place.
The problem I see is you are going to have different expansion rates between steel and epoxy. That would be the end of the epoxy, along with the heat itself.
The differing expansion rate between materials is probably why nobody has successfully developed a plating process to restore old barrels.

Best,
Ted

Thanks, Ted, but I'm not going to try this. I don't want to steal AZMike's thunder.

I just suggested the Belzona only because it is the best epoxy for steel repairs that I know of, and because I just enjoy thinking outside the box.

Best, SRH

If that's a big issue, how does Belzona work so well on engine blocks, etc., in industrial applications where expansion of steel is a fact of life? I know personally of a tractor engine that has been running for several years with it in place.

I would guess the tractor in question has a cooling system, likely liquid cooling, that keeps the expansion in the repaired area under control.

I wouldn’t bet heavily on a repair in a combustion chamber, exhaust port, or turbo housing.

Best,
Ted

From the Belzona 1511 data sheet ........

Key technical data:
Working life at 25°C (77°F) 60 minutes
Pull off adhesion on grit blasted mild steel (ASTM D4541 / ISO 4624) 5180 psi (35.7 MPa) 20°C/68°F cure

5160 psi (35.6 MPa) 100°C/212°F cure

4700 psi (32.4 MPa) 160°C/320°F cure
Tensile shear adhesion on grit blasted mild steel (ASTM D1002) 3060 psi (21.1 MPa) 20°C/68°F cure & test

2780 psi (19.2 MPa) 100°C/212°F cure & 20°C/68°F test

2980 psi (20.5 MPa) 160°C/320°F cure & 20°C/68°F test
Temperature resistance 160°C (320°F) immersed, 210°C (392°F) dry
Bonds to Steel, stainless steel and other metals
Typical applications Metal repair and pit filling for equipment operating at high temperature


I'll bet the company has thought about heat expansion of the base metal.

SRH

Cold Iron is the Naval Engineering term for the ships plant being shutdown and hotel services are being received from the pier. Meaning you are not out to sea anymore. I've been using that handle since I retired from the Navy 25 years ago. As a propulsion engineer.

Been doing computer systems since 1976 also with APL my first language and have been doing only IT for the last quarter century so have no idea where Belzona stands now as far as composition and application or if it has even changed. But at one time I earned the nick name Belzona King I was pretty damn good with it. And yes did repair a lot of pumps with it when out to sea with limited resources. Belzona was (and is) expensive so I kept it under lock and key.

If flanges allowed would weld and build up the metal then file and shape it back down to mate surfaces. Pump shafts, impellers etc. are different alloys and shapes and don't always allow that luxury. Belzona to the rescue. Would not use it on a 975° 1200 psi system if I could help it. But was always amazed at how well it worked no matter what the application was.

Not sure I would be brave enough to use it on a gun barrel though. I too am looking forward to the results.

I wasn't trying to rain on anyone's parade Stan. I was merely giving my opinion from the perspective of a lifetime of fixing things, and my knowledge and experience with epoxies. I'm glad Ted mentioned the thermal insulating properties of the space shuttle thermal tiles.

I'm also glad you provided the temperature and pressure tolerance data on the Belzona epoxy, which I have never used. You will note that the pressures are well below what would be encountered in the rear portion of a shotgun barrel, even though the duration would be as brief as the temperature extremes of hot powder gasses. Then you also have the added component of friction from the shot column and wad moving across your epoxy repair at 1000 fps or more, and powder residue from previous shots scoring the epoxy, which is much softer than steel. You would not encounter this in any centrifugal pump, and even those temporary repairs are not intended to equal normal pump life expectancy.

I also considered the repeated thermal expansion and contraction, and the very real possibility of separation or delamination causing a partial barrel obstruction, and resulting in a bulge or burst. Of couse, if that happened, we could always have one of those fun entertaining barrel burst analysis Threads!

Even if this experiment worked OK in the beginning, would you want to be the unsuspecting buyer of this gun several years down the road.. not knowing that you'd better check the bores after each and every shot??? And that brings me to the same thought I share with Bill Shodlatz. How many unscrupulous individuals might try to do a Bondo job on pitted barrels to sell a gun that has questionable pitted barrels?

At work, we are constantly tossing out and debating ideas. Many are shot down after a little debate and consideration of the ramifications. Some sound very good on paper, but are not at all good in practice. Some end up creating worse problems that they were intended to solve, and some are downright dangerous. Then we have the winners that make us keep trying. I think this idea is just dangerous, and best shelved permanently. In the final analysis, many guys simply worry way too much about minor pits that look much worse than they are. And some barrels reach a point where they need to be removed from service.

Forums are the table at McDonalds where the old guys get together to bull shit in the mornings.
I have an 1882 Remington with pits in the steel barrels, if I can afford the epoxy I'll try 1 barrel with gunsmith Rick Dunbar's help and very careful shooting and checking.
I have no intent to dupe anyone, that's not the way I roll.
Thanks all for the thoughts and ideas (over coffee)!

Yep, it's fun discussing stuff like this. I have grave doubts about the efficacy of this type "repair" but if Mike's willing to give it a go I'm all ears as to the results.

I doubt if Mike, or anyone else here, would try to salvage, in this way, a barrel that was deemed unsafe because of extreme pitting. I certainly wouldn't. If it were to last for any considerable length of time it might spark an idea for a repair on something else one day down the road, that we would never have thought of otherwise.

If it doesn't last indefinitely it doesn't mean the idea was a failure. It just means that potential method/product has been eliminated by actual trial. That's often how useful discoveries happen.

SRH

az, let us no watt appens...

This is just so much fun....

This has got to be just about the silliest crAp I've ever read on the internet.

Stanleys Belzoni Balogna epOxy.

And ole E D chopping at the heels to see if it'll work to go along with his torch jobs.

Fire an E'poxy don't mix...

There seem to be a host of high temp cements, epoxies, and various other coatings that may very well fill in pits. Some of them may be more costly than a new gun I suppose, but perhaps several have some utility for this purpose.

http://www.sauereisen.com/ceramic-assemb...FBoCuiEQAvD_BwE

Didn’t Teague stop putting liners into barrels because they had problems with the adhesive system? Not clear if the problem was as getting an even, end to end coverage, for and barrel and liner or was it the bond broke down over time? It would be interesting to try pit repair as described above. What do you really have to lose?

jOe's approval?

Winchester brought out the Model 59 shotgun in 1959. It had a fiberglass wrapped barrel. I am not too sure how it relates to this subject but I'm pretty sure a jam-o-matic can get hot!

This article doesn't say the adhesive was the main problem. Other issues like repairing barrels with the liners were a problem along with some reviling with the liners. I wonder what adhesive was used for the liners. Teague Liner issues

Ken

Wrong thread

I doubt any epoxy finely enough applied Would stay stuck to a pit The strain of the barrel as it bulges during firing Would probably pop it all loose in short order

Yes, with a steel liner taking the brunt of hot powder gasses, pressure, friction, etc. There are also rifles using a similar system with a rifled liner wrapped in carbon fiber and high temp resin. This is like the difference between using epoxy to patch an engine block because the water jacket leaked, and trying to use the same product to line a scored cylinder.

KY Jon asks what you have to lose??? If the veneer of epoxy pops loose and creates an obstruction in a barrel already somewhat compromised by pitting, you could lose digits or an eye. A lot of dangerous experimentation has taught us about things like the strength of Damascus barrels. But when the risk became greater, the firing was done with a string pulling the trigger, and the shooter shielded behind a protective barrier or a big tree.

I think that the eventual failure probably won't result in a barrel burst, but the possibility certainly is there. Most likely though, you would simply learn that an epoxy interior surface is simply not up to the task, and it will never be a satisfactory replacement for sound steel in this particular application.

I figured Steve'O (SKB) would pipe in after all he was the American connection to Teague barrel liners at one time...at least she said he was.

I took a model Winchester Model 59 to Columbia for doves countless years ago. No problems but the epoxy holding the ramp and front bead failed after the first day.

I think the idea has some merit. I spent my career in the aerospace service industry and was tasked with finding safe and economical repairs due to design issues, corrosion, failures, etc.
I wouldn’t dismiss the possibility of using some of the latest super epoxies or other products that have come out in just the past few years.
I have also thought of repair ideas that might be used to repair barrel corrosion and pitting.
We repaired some high dollar landing gear struts that had internal corrosion by machining the internal barrel of the strut and have the barrel chromed. Could this be done on a shotgun barrel? I’m not sure.

Could a thin metal sleeve be hydroformed inside the barrel after back boring? Not sure.
Could a barrel be back bored and then heat the barrel in an oven, super cool the sleeve using methanol and dry ice then press the sleeve in for a interference fit? No bonding agent needed possibly eliminating the issues Teague experienced.
Wouldn’t resolve the issue of making a dent non repairable but if you had a unserviceable barrel to begin with you got more time out of the barrel then you would have in the pitted state you are ahead of the game.

I guess Steve swore an oath of Teague Silence...

Did you have a question that was not covered in Dig's article? I am happy to share what I know about Teague liners and have done so in the past.

I've always thought chrome lining might be a solution to this problem. I don't know much about the process. If it was feasible it would already, probably, be being done. Any thoughts ?

Sure. Hard chrome plating the inside of pitted shotgun bores would involve first machining out the pitting, as was done in the case of the high dollar aircraft struts mentioned above. You cannot fill in pits with plating, and get a smooth surface. Then the bores would be nickel plated, followed by a hard chrome plating of not more than .005". Going any thicker would lead to problems with the chrome surface, which is much more brittle than steel. I can't imagine that .003" to .005" of chrome plating will make the barrels any stronger, especially if you honed out that much or more prior to plating them.

I have no idea how this would be accomplished on an intact set of double shotgun barrels, i.e., how this could be done without plating the outside or affecting rib solder joints, etc. This may have been economically viable on high dollar aircraft struts, to prevent future internal corrosion, but likely wouldn't make any sense whatsoever on a set of old pitted shotgun barrels, unless the gun was rare and very valuable. Anyone want to speculate what sort of valuation hit a Parker A-1 Special or Lefever Optimus grade would take if you chrome lined the bores???

The idea that any currently available epoxy as a bore lining would have merit would be quickly dashed by simply taking a sample of the epoxy and comparing the surface hardness to the hardness of typical shotgun barrel steel. Then compare all of the other attributes of steel that make it the universal choice for gun barrels. It is wishful thinking to believe that an epoxy lined bore in a shotgun barrel would last, given the temperatures, pressures, and friction involved. Even when these materials are used to repair pitted surfaces in a cavitating centrifugal pump, for example, the repair is regarded as a temporary fix until a replacement can be acquired.

If I'm going to dream about something, I'll dream about winning the Powerball Lottery Jackpot, and then buying a really nice shotgun without pitted barrels.

There was an outfix in Charlestown, IL that crome plates barrel i.d."s. The first coat was copper to provide a base for the chrome to stick to. Perhaps that base coat could be applied heavy and the hone to hid the pits?

bill

I couldn’t care less about a pitted barrel unless they’re extreme. Small ones have virtually no weakening effect on strength or performance. With proper cleaning, modern powders, primers, and plastic shot cups pits are not going to grow. When buying a real vintage gun I tend to run backward (long experience) when a seller says the bores are perfect without a single blemish. Bells ring all over and I hear “honed”! Now I have to worry about wall thickness, quality of honing, and all sorts of stuff. Give me a frosted barrel anytime over a perfect bore.

watt joe said...

The only currently available technique I hold out hope for is some form of spray welding to restore the barrel's interior to solid, uniform steel.

Tubing/sleeving into the breech of a gun is very viable, esp. with TIG welding. But, properly done, it isn't inexpensive. There is a fairly broad range of guns that can get a "second run" via this technique at a reasonable return on the cost. Bottom of the heap guns are best consigned to a comfortable place on a wall or over the mantle. Top of the heap guns should have new barrels, spankin' new from a time served barrel maker.

Chrome plating is common for extra runs of aircraft engine cylinders. I don't discount an adaptation to gun barrel repair.

DDA

I know of no currently available spray welding process that could be used inside even an 8 gauge bore. 12 gauge or smaller would be out of the question. I've seen a couple different spray welding processes in use, and the size of the equipment, and the requirement that the arc or plasma spray be applied perpendicular to the surface being repaired, would preclude filling even one pit inside a barrel, let alone lining and restoring an entire bore.

Spray welding isn't even used to build up and resurface worn out ways on lathes, because it will delaminate at the thin edges when surface ground or scraped. The molten metal droplets spread out and stick to the surface, and to each other. But there is not the same type of fusion to the base metal as in other welding processes where the base metal is actually melted.

Then there is the little problem of the heat generated during the process. Even the lower temperature arc and combustible gas processes would heat the barrels hotter than the melting point of the solder used to join double barrels. The plasma spray process, which would give much better adhesion and a more uniform surface, is much hotter than that.

Maybe someone will someday miniaturize spray welding equipment to the point that it could fit inside a long small diameter tube such as a shotgun barrel. And maybe someone will also develop a process to inexpensively 3-D print a new set of barrels that would perform safely. Right now, both ideas are nothing more than dreams in the distant future.