Just to add to what Steve is talking about, the hole for the pin needs to be a SLOT, fore and aft of the center of the hole. Swelling and shrinkage of the wood during seasons of the year can put enough pressure on the pin to stress the solder joint, if this is NOT DONE. Occasionally, solder joints will fail, or "pop" off the lug, under that stress, particularly if a poor solder job was done, or soft solder was used.
Solder, applied properly, will normally hold the lug from being pulled away ( at 90 degrees) from the barrel. However, It does not usually have that same capability to withstand SHEER forces- as in a parallel-to-the-barrel pressure placed on the joint. A Silver solder-- rather than ordinary plumber's or Electrician's solder--- which requires a higher temperature to melt, is preferred. To protect the barrel, tin the barrel and tin the lug with solder. Then clamp the two pieces together, and apply the heat to the LUG- NOT the barrel.
To protect the barrel during "tinning", simply wrap wet rags around the barrel both front and behind the location of the solder site, to act as a heat sink. That will prevent any possible damage to the barrel.
If the lug is too close to the muzzle, put a wet rag inside the barrel at the muzzle to act as a heat sink. Just grease the bore before putting the wet rag into the muzzle, and remember to remove it and dry the barrel thoroughly with dry cleaning patches when you finish soldering. :thumbsup: