Measure the ID very carefully so when you turn a shoulder on the extension barrel it will be a very close
fit.
SHOULDER ANGLE
The shoulder angle has to be very accurate, so the fit between the two barrels will be exact. The length
of the shank on the extension barrel has to be exactly the right length, so it will but up on the shoulder on
the inside of the barrel as well as on the outside.
When you have achieved this fit, and have the extension barrel turned so it will just fit the counter bore
with no play, it can be soldered.
You can get paste, low melting temperature silver solder from most gunsmith supply business. Coat the
inside of the counter bore, as well as the outside of the shoulder of the extension.
If you have a slightly loose fit, you may need to make a mandrel that will just slip inside the bores of the
two barrels. This will keep both in line while soldering and cooling.
Carefully heat up the outside of the barrels after they have been combined. Be sure to keep the heat
uniform all around the barrels, and when the solder melts evenly, let cool. Test the barrel after it is
cleaned out to make sure you have a good soldering job.
On all the different lining jobs that are listed above, be extra careful when first testing. All of these