doublegunshop.com - home Forums Thread Like Summary - SxS forearm lug failure

I have a SxS with a problem. The fillet in from of the lug is detaching slightly and I suspect the lug has moved slightly since the ejectors are not working properly. Gun too old for warranty repairs.

Questions-
1-What causes this? [It has happened on three other guns in the last 20 years.]
2-Can it be avoided?
3-Who might be a good choice for repairs?

Thanks in advance for your suggestions.

The lug is sometimes less than well fitted to the bbl contour. The sweat solder attachment process lacks strength and soft solder is a very poor filler material.
The J-Spring type forend attachments put a lot of forward tension on the lug when snapped into place. They keep the bbl pushed forward nicely, but at the expense of pushing hard against that lug to do that.

The latch type can pull the lug out if the fit is not correct. Too awful tight where the latch doesn't close and needs a slap to close is just pulling on the lug to close the forend tight to the bbl pulls on the forend lug..

..and sometimes the old solder joint just gives way. 100yr old soft solder joints that are under some tension can do that.

The reinforced lugs with their extended & sometimes wider short ribs to the rear help with greater contact for soldering.
But fit is still the primary need as a sweat solder joint is useless w/o it. A thick layer of soft solder betw the two surfaces has little strength.

Here's some pics of a couple lug failures. You can see the poor solder contact betw bbl and lug on the one.
The lug(s) get loose and move forward pushing on the bottom rib loosening it and crumpling it
at the same time.
So straightening the rib and re-solder of it is usually needed.

Careful cleaning of the surfaces is needed. I used a simple scraper most of the time. The old solder and flux shaves off easily as does the soft steel the parts are made of.
The bbl surfaces clean up easily with scrapers as well. Much easier to manipulate than files IMO.

I use a Propane Torch hand held like a plumber would use.

When things are fitted, tinned and then clamped into place, I place extra clamps on the ribs out from the area that needs reattaching.
That way if the heat starts to melt and flow that solder, it's still in it's orig position and held there. It just cools back down with everything else and all is well.

The amt of heat needed to sweat solder these repairs is not tremendous. Sometimes I do not place extra clamps around and just clamp the lug if it's a small one.

Proper heating for soldering is to heat the metal around the joint, not the joint itself. That avoids burning the flux and overheating things which just causes a poor joint.
Many people get in a hurry and over heat things thinking they have to be especially quick about it or the entire bbl & rib assembly will come apart and fall to pieces on them.
Not true.

If I'm resetting ribs on a bbl that are entirely detached, I will clean the ribs with a scraper of the old solder and flux. Then use a heavy duty elec soldering gun ( I think it's a 200W (?) pistol grip soldering gun) to tin the surfaces.
That goes extremely fast, clean and easy.
I also use the same steel scrapers (like stock inletting scrapers) to clean the bbl surfaces also.
Just home made out of drill rod. Flattened, bent to L shape when heated red. File to shape, Harden and temper and put a file type handle on it
A Flat and a V shape pretty much cover the needs.

With the scraper you can pull it and shave the old solder right off of the surface and a micro shaving of steel at the same time leaving the surface a perfect condition for flux and tinning.
The removed rib usually shows a line where it was soldered to the bbl. With a scraper you can shave the bbl clean right to that old line.
Scrub outside that line with a common soft lead pencil and that steel will not tin.
Then go ahead and tin the scraped clean area. I also do that with the HD soldering gun . It sometimes doesn't quite have the power to tin the bbl's when they get thicker up by the FE lug.
Then I use an old time soldering copper with a sharp point on it heated and tinned with the propane torch to finish up that last little bit and do the Short Rib attachment area.
Regular paste NoCorrode flux from the DIY store and 50/50 Lead-Tin solder.

FYI-- Kirk Merrington closed up shop and retired last year. He was probably the best shotgun barrel man in the country. I wish him the best with his health & retirement.

I was wondering how you did that. I used to work in a shop that rebuilt starters and alternators for trucks and cars. I used a large soldering iron about 14"- 16" long to resolder armatures for the big truck starters. It took forever to do one of those. I was always pretty good at soldering with a smaller Weller soldering gun. But putting a torch in my hands around a shotgun is asking for trouble. I know better than to try that. That is really an art that you can do that. Good for you that you are that skilled. So, I was just wondering. Thanks.