Make sure your side-to-side alaignment is correct also. The rear tang can be positioned correctly according to the rod and measurement, but can stillbe slightly kicked out to one side or the other and won't fit back down in the orig inlet.
A simple straight edge can check it,,if the inlet in the stock corresponds to a straight line as well.
The soldering must be done to absolutely clean metal.
A butt joint will hold OK in this position as there is no pressure on it once the guard is in position and if the graud and tangs sit into their inletting cuts w/o any need to push one or the other into place using the screws as jacks to do so.
Adding a small, short plate on the backside of the joint will substantially increase the strength of the joint. It can be filed and shaped so as not to show as a second full layer of material.
Flux the ajoining surfaces before clamping.
Flux the entire area around the join after clamping into final position.
You must get the joint hot enough,,that means somewhere around 1200F to 1400F as a general rule for Hard Solder/(Silver Solder).
Burning the Flux is a common mistake when Hard Soldering,,even when Soft Soldering.
It means that the Flux is heated too high and it looses it's protective quality to keep air/oxygen from the surface of the steel.
The result is that the steel surface developes heat scale and the solder will not attach itself.
The Flux as it is heated will at first start to 'grow' and expand. Then run a little. But as the heat increases it will retract back to the surface and then start to turn into a clear glass appearing liquid covering on the steel area where applied originally.
That's what you want.
When the temperature you are heating the metal and the flux reach the correct point where the solder will melt and flow,,simply touching the tip of the solder wire to the joint will immedietely melt the wire and the solder will flow all over the fluxed area and into any of even the tinyest cracks. That's why fluxing the joints/cracks before clamping the assembly together for soldering is a good idea.
You can while heating the metal keep touching the solder wire to the metal to find the point where it does in fact melt and flow.
Or you can cut a small piece of the solder wire and actually wrap/twist it around the joint before covering it with the flux on the outside of the area.
That's been mentioned as a technique already LynnC where he plants a piece of solder in the flux so it wouldn't fall free and it melts and flows right into the joint on it's own
It will melt on it's own when the heat is right. You can still add a bit more with the solder wire if you want to if you think it needs it.
I often when using the tip of the solder wire, warm the end of the wire for a quick second in the torch flame and then stick it in the flux. It will catch a bit of the flux on the end of the wire. Just an extra bit of the flux into the joint along with the solder wire when I apply the solder.
Once the solder flows and it looks good,,you are done.
Don't 'play with the solder and try and make it look pretty'.
You can quickly over heat it that way trying to get it looking fancy. The joint is already at somewhere in the 1300F range. It doesn't take much more torch time to spoil the soldering job. You can still burn the flux off and destroy the soldered join at this point.
Pull away and let it cool all by itself.
No water cool down,,no air blasts. Just leave it alone. If it's clamped up in a jig,,leave it in the jig till cooled down.
The glass like flux around the joint will come off by placing the piece in plain boiling water.
Let it boil for 20min or more.
Some of the toughest stuff may need some help at the end to remove by a simple wire brush or wheel will do.
Heat scale on the steel can be removed by then placing the part submurged into plain room temp water with muriadic acic in it.
It doesn't need to be very strong.
A 1/2 Gallon of tap water,,,2 tablespoons of the acid is all I use.
I have an old Tupperware container with a snaptight lid that I keep the soln in. I keep reusing it over and over.
Some use more acid,,it will work quicker of course. I can wait.
Use at room temp..do not warm! Warn soln will cause very quick reaction but can pit the metal before you know it.
The heat scale will slowly turn jet black. What doesn't fall off on it's own, you can wipe off with your fingers. Might take a couple hours or more.
The very low acid concentration will not pit the steel. It will come out with a French Grey color.
I wash the part(s) with soapy water, rinse hot water then dry. Then oil if leaving them for a time.
The 'Silver Solder Paste w/Flux' shown by Eric is actually Silver bearing Soft Solder. It is usually around 95% Tin and 5% Silver.
The carton states 450F melt temp for the solder and that is what that Tin/Silver Soft Solder works at.
Hard Solder (what we used to call 'Silver Solder') is the 1200 to 1400F melt/flow temp solders.
The Silver bearing Soft Solders do work remarkably well and are a bit stronger than the Lead/Tin alloy soft solders.
Those that are mixed like the one shown as a fine metal dust pre-mixed with their flux are very easy to use.
There are some Hard Solders that are (were?) sold that way. Don't know if they still are..
One thing about the Tin/Silver soft solders is that they stay bright-white. They never oxidize like the Lead/Tin soft solders.
The bright white line sometimes makes no difference on a hidden solder joint. But at times, the solder line is visible and the Lead/Tin solders do oxidize and turn a dark grey/black over time naturally. Looks better than the bright white line in many applications like sight bases and SxS ribs.
I believe there may be chemicals that can be used to color the Tin/Silver solders I think. So there is that possibility.
There are some to use to color the Hard Solder as well,,or at least they used to sell some. Many of them will oxidize to some extent on their own so they do not remain a bright solder line.
I do like the solder-in-flux mix though. Very handy to use.
