RIC barrel bushing/sleeve

[Surpmil]

Silver solder os great stuff, but you have to be REALLY careful not to overheat things with the torch and cause evil things to happen to the bore at the muzzle.

One old trick is to pack the relevant section of bore with charcoal and then SOFT solder, after thorough cleaning, fluxing and tinning the barrel and the interior of the collar.

I'm sure there are folks MUCH more "crafty" than I am, who can provide greater detail.

So what does the charcoal do? I wouldn't have thought it would be very good at drawing out the heat. A close fitting brass rod of as long a length as possible in the barrel, and wrapped with some brass shim stock to make it tight under the area being soldered, that might draw enough heat away.