What in the underlug?

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smokeum54

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Started my monthly barrel swabbing this morning, 3rd gun i grabbed, (Cabela's investarms) the wedge key fell right out. Pulled the barrel to find this.
This gun hasn't been shot in close to ten years but it has been shot alot in the past. Every few months i pull most of my barrels just to check for rust and the last time i did this one it went in like normal. I fit all my wedge keys for a firm push with my thumb or just a light tap with a plastic hammer.

Looks like it just decided to give up and let go. Guess i have to dig out my dove tail jig and another underlug.

I currently have 8 investarms and between me and my dad we've bought, used and sold several others over the years and this is a first for me. Anyone else ever have this happen?

On a side note, my old investarms fancy hawken has a dove tail style lug, maybe they should have kept doing that 🤔
20241019_105449.jpg
 
Had the same thing happen to a gpr. You can solder it back on. I think the factory did some sort of weld. I tried to remove one once with heat and couldn't release it.

Maybe from gradual creeping corrosion.
 
Had the same thing happen to a gpr. You can solder it back on. I think the factory did some sort of weld. I tried to remove one once with heat and couldn't release it.

Maybe from gradual creeping corrosion.
Im a darn good welder, brazer, but soldering is my nemesis 😆 just always gives me fits. New dove tail probably best for me. I thought about gradual corrosion to but the break looks perfectly clean. Guess the gun just wanted some attention from me 😁
 
From the look of the barrel, it looks like solder. However the under lug looks like J B Weld. I have silver soldered several under lugs and ram rod pipes back on, the main thing is to get the area to be soldered squeaky clean and tinned.
Good catch. Looked at it under some better light and did a little poking with a screw driver and there is a little bit of JB on the barrel. Must of came off some time before my dad got it and that's how they fixed it. It held up pretty good considering how much my dad shot it back when he got it.

I do know they came spot welded from the factory. Here's a extra barrel i have in the white, with patina and you can see the blueish heat marks from the weld.
20241019_153516.jpg
 
Not sure what you have to work with, but it could be tigged on pretty easily and silver solder will work well too.
I wish I had a tig welder. I'm good with my mig and brazing but like I mentioned earlier, me and sloder have issues 😂 Found a dove tail style lug that will work, now I just need to find my dove tail jig. And with as much as my nieces have been bothering me lately, i might get it done in two weeks 😏
 
I’ve owned a few Investarm made guns that failed similar, and have seen a few others. All the failures appeared to because of poor spot welds. Prefer correcting with a dovetail in the barrel, though a tapped holes or a staked lug can work. I’ve just seem too many tapped holes and lug holes drilled too deep and end up in the bore to consider either a good option unless one is a skilled machinist.
 
That's why I cringe every time there's a post about a loose wedge on an Investarm gun & invariably someone will recommend tapping on the underlug to tighten it up.
 
I solder underlugs and front sights on my smoothbores with solder paste, never had one turn loose even when I tried to knock an underlug off with a hammer to see how well the paste would hold.

Super easy to use, I do file the mating surfaces to be a close match, I use a propane torch for underlugs.

silver solder paste.jpg


soldering on a lug.jpg


I broke off a bit deep in the wood in a trigger guard lug on the same gun, I had to destroy the lug to get the bit out. I made a new lug for the trigger guard and soldered it on with the paste, 10 years down the road there have been no problems with my fix.

triggerguard underlug.jpg
 
So many options when it comes to underlugs. Honestly you already have the parts. Soldering is your best option. Silver solder and acid plus a good torch. 99 % is preparing the surface. Don't get the metal too hot thats what most people do. Grab a piece of steel and practice on it first. Watch some utoob videos on Soldering also. Good luck!
 
I have a question about the Solder-it. Is it an epoxy or is it just a very low melting temperature solder? The reason I ask is that it is very difficult for me to silver solder on old somewhat pitted surfaces like a front sight repair or replacement on an antique.
This is because I don’t want to file or buff too much on antique metal surfaces, which would make silver solder much easier. If the Solder-it is like an epoxy, I can see how that would work really well under less than ideal circumstances.
Old Shepherd
 
@Old Shepherd It is a low temp solder paste.

Buff the area as well as you can with a file or emery cloth, blast with air, then clean well with a residue-less solvent. I like to use starting fluid. When dry, apply the paste to your part. The flux is already mixed in. Clamp your part and heat with low flame until you see it flow.

I have used it on lightly pitted antique pieces with good results. Broken front sights, ramrod pipes, underlugs, etc.
 

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