7mm Sight Base Replacement

[nijalninja]

G'day there, as usual I am here asking for some wisdom with a repair.

I have a 7mm Brazillian with a hacked to bits rear sight base, and I also have a new sight base to replace it with. Now I have heard it said by plenty of people that to get it off you need a plumber's torch to heat it up and loosen the solder under the base and in the screw threads (Supposedly Lead Solder), and that you need to take the foresights off before the rear.

But now the question is: How do you get the new sight base on? As in how do you apply the solder back to it like it was before but with the replacement base? I can't think of a way to get the solder in there evenly.

Cheers to any help, this will get me one step closer to having my 7mm back to nice condition.

Information

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[rcathey]

There’ll likely be a bit still stuck on the barrel.
When you put the new base on and heat it up, capillary action will wick PLENTY around the barrel to hold the sight on. Wouldn’t take much.
Just like soldering copper pipe together.

[wjw]

To get a good joint one needs to clean the old solder off, flux and tin the area where the sight will fit with just a wash of solder, then flux the inside of the sight and position. Heat the sight and barrel and when hot enough, add solder by touching it to the area where the sight and barrel meet. Capillary action will draw the solder into the joint. Not cleaning and fluxing will at best result in a poor joint and usually causes a mess. Be advised that the flux will remove the finish, so try to only flux the area under the sight.

[nijalninja]

rcathey, I have no idea what capillary action is or what it is like soldering copper pipe but I will look it up. Cheers.

wjw, not sure what flux and tin is but I'll look it up thoroughly. I don't think there will be any finish under the sight base anyway. Thanks a bunch.

[nijalninja]

So as I understand it: I have to heat up the front sights to get the solder loose, remove a screw under the blade/dovetail and it should drift off (brass drift), the do almost the same at the rear sights. Then I heat the areas where the sights sat and wipe off the old solder, clean these areas with some kind of solvent (Isopropyl alcohol maybe), then flux the areas on both the barrel and inside the sights, then add a small amount of solder to both the sights and the barrel before mounting the sights, then mount the rear sight base and align it with the screws, then just keep heating the barrel and sight base until the solder melts easily and is absorbed under the base by capillary action, then just let it cool and clean up these areas and replace all screws and whatnot.

Sound right? Only questions I have are what solder to use (50/50 or 60/40) and what flux to use. If someone can help me there then I am all good to go.