JDW,
Good stuff. The Galazan barrels seem to be in the 'normalized' condition. This is just a bit harder than full anneal. This is an acceptable condition to weld without worrying too much about cracking. When annealing the welds, the temp rises high enough to stress relieve the weld and adjacent heat affected zone. Using low carbon mild steel filler rod helps keep the stresses down also, since it will yield more easily than higher alloy steel.