How to test solder job on soldered on front sight

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Potashminer

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Today I managed to get a front sight stuck onto a barrel, on purpose. I scraped the bluing off the barrel, fluxed it and "tinned" with solder. Did the same on underside of the front sight ramp. Invented a spring loaded "holder" to keep tension on that sight ramp as the "tinning" went fluid. Put generous coat of flux between and levelled out that sight ramp under that holder. Finished the job. Did not fall off when the holder was removed. Cleaned up the barrel - looks like it belongs.

So, what is a recommended way to "test" whether that ramp is truly stuck on there? I used some of that 5% silver / 95% tin solder, with the appropriate flux. Did not add solder as I was heating - relied completely on the "tinning" to stick together. I have one spot, perhaps 1/8" wide where I can see tiniest bit of solder at the joint between barrel and ramp - other than that, no sign that there is solder under there. I intend this one to be used with aperture rear sight, do not want that front sight to go missing. How to verify that?
 
So a "properly done" job should be able to take a hit, like with a hammer, and not come off? No idea about this - my first go-round with installing one that relies only on solder - no screws.

Edit - from manufacturer of the solder - Harris, says it has 10,600 psi shear strength for "copper lap joint" - could not find similar value for steel lap joint. The ramp is .315" wide x 2.75" long, so that is .866 square inches. Even if I only got 75% of that, still is about .65 square inches which should still be about 6,900 pounds in shear. Sounds like should be a good joint? No idea if that is a lot or a little for a front sight ramp?
 
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Potashminer said:
So a "properly done" job should be able to take a hit, like with a hammer, and not come off? No idea about this - my first go-round with installing one that relies only on solder - no screws.
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I am not any kind of authority on any of this but I think if you hit something hard enough it will come off regardless of how good the job is.
 
I would suggest a hardwood dowel between the hammer and the sight... and hold the barrel firmly in a padded vise... One good blow should do it... and if it holds the sight will not be marked up...
 
If you have enough heat, all the crap was cleaned off, tinned right, it should be fine, wack it with a plastic screw driver handle.
You could have added a drop of solder, but it is done.
 
devolut said:
I am not any kind of authority on any of this but I think if you hit something hard enough it will come off regardless of how good the job is.
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This!

If you doubt the job, redo it.

While my response was somewhat tongue in cheek, it's about the only way to test stuff like that. Once you destroy the parts, you see how the joint covered and you see how the solder sticks.

Seriously. There really isn't any other way to actually "Test" a solder joint like that.

At some point you just have to have a little faith in your prep and process!

Practice pieces go a long ways to making the confidence rise!
 
OP,
Your best option would be cadmium silver braze instead of 95/5 soft solder.

Give your soft solder job a tap w/ a dead blow hammer...lightly...no slap shots!!!!!
 
Dan, what temp do you need for that alloy?

I understand it can be used over old solder joints. Other than fusing and wiping the old stuff away, any special prep required?

Thanks,
Ted
 
I silver soldered a set of rifle sight on a 14” shotgun barrel last year, once it cooled I hit it with a rubber mallet a few times and a 2”x2” length of fir I split from my fire wood pile. It didn’t pop off, have hunted with it last year and put a few boxes of slugs through it. I flowed enough solder into it that there’s a nice visible line of solder around the edge of the sight bases.
 
Why not? said:
Dan, what temp do you need for that alloy?

I understand it can be used over old solder joints. Other than fusing and wiping the old stuff away, any special prep required?

Thanks,
Ted
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Never attempt to flux over silver brazed parts to reattach.

Start from scratch by prepping/removing all old silver braze.

Cadmium type flows better than non cadmium type silver braze.

Do not mix flux from one manufacturer w/ another manufacturers braze compound.

It's brazing not the slang term of soldering....aka 1400degrees F scale.

If one needs/attempts to soft solder any firearm part,just epoxy the parts together,since clean-up will be easier & require no heat or technique or skills.
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Ideally one side of the tinning would have been left with a little bit of filler solder. Not much but just enough to cause a very small fillet around the edge of the joint. Sounds like you brushed it off and left just a film.

The good thing with solder like this is that you can re-apply the spring widget and re-heat and re-flow the solder in the joint and add a touch more and it will flow in and fill any slight gaps you might have. The tinning you did should have protected the surfaces. I'd still use a touch of flux but you'll only need that, just a touch.

If it's one of the bases that is roughly 1/4 to 1/3 the width of the barrel and you got a proper radius on the underside so the joint is fairly thin and provided the joint isn't really badly starved for solder it'll easily withstand the bump with a dowel and hammer or a good whack with a plastic handle screwdriver. Soft solder is a lot stronger then many folks seem to believe. Especially for something with a low profile like this and with somewhere around a 1/2 square inch or slightly more of surface area for the joint.
 
I would hit it with a rubber mallet lightly then ramp it up a bit until your satisfied it won’t come off. Better to do this in a controlled environment so you don’t lose it in the field where it will be like looking for a needle in a haystack. Doh!
 
I finally successfully soft soldered a front sight ramp on my .308 Husqvarna this spring. I tested with the wooden dowel, hammer, barrel clamped in padded vice method. Wacked it pretty hard. Before this a talented friend had soldered the sight; shortly after I was drifting my front sight with my Williams sight pusher and the ramp popped off. Before this I had attempted to solder with Brownells silver solder several times and was never able to tin as I could not find the right flux. (Brownels can't mail theirs to Canada). Before this I had glued the ramp with JB weld. Lasted a couple years, but one day when I was off hand shooting I felt something fall down the front of my shirt. It was my sight ramp. Before this I had sent the rifle out to a gunsmith, who soldered it on. The ramp fell of shortly after that.
 
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For solders and fluxes - I am by no means expert, but was pretty much emphasized to me by guys that are expert, that the flux has to be appropriate for the solder - no getting around that. Pretty certain from Amazon, I found Harris brand solder - spec'd at 3.4% to 3.8% silver with the rest tin - pretty much identical solder to what Brownells sells as Force 44. Bonus to me was that the Stay-Brite flux, for that solder, was also available, and all came to me in the mail.

Very much learning there are similarities to gluing wood - a joint starved of glue or solder (too tight fit or too tight clamp) will not hold; thick layers of it do not add to - might even detract from - the holding strength. And very much have to plan ahead for dealing with the "overflow" - a real PITA to remove after, if you did not have a plan!!! Read somewhere to coat area that you do not want solder to stick to with "soap stone" - the white stone marker that welders/metal workers use - even with flux leaking all over it, the excess solder just balls up and rolls off - works well!
 
Potashminer said:
For solders and fluxes - I am by no means expert, but was pretty much emphasized to me by guys that are expert, that the flux has to be appropriate for the solder - no getting around that. Pretty certain from Amazon, I found Harris brand solder - spec'd at 3.4% to 3.8% silver with the rest tin - pretty much identical solder to what Brownells sells as Force 44. Bonus to me was that the Stay-Brite flux, for that solder, was also available, and all came to me in the mail.

Very much learning there are similarities to gluing wood - a joint starved of glue or solder (too tight fit or too tight clamp) will not hold; thick layers of it do not add to - might even detract from - the holding strength. And very much have to plan ahead for dealing with the "overflow" - a real PITA to remove after, if you did not have a plan!!! Read somewhere to coat area that you do not want solder to stick to with "soap stone" - the white stone marker that welders/metal workers use - even with flux leaking all over it, the excess solder just balls up and rolls off - works well!
Click to expand...

When I watched the brownells videos on how to do it, the guy used cold blue around the edges of the solder joint. That is what I did and it worked well keeping the solder from flowing out. Sounds like soapstone is a good trick too!
 
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