Ted - welding has to do with cosmetics, not safety. A carefully welded and struck seam is near invisible. The issue with this work is that some may pass it off as OE barrels, knowingly or unknowingly.
E330 - Most sleevers would, as far as I can determine, prefer to make some extra money with the striking you refer to. However, most customers are aware of the reduction in value of sleeved guns and specify a cheap job (unwilling to pay for careful striking or more than minimul bore work). Note that very few guns handle today as they did when they left the works. Most, especially the sleeving candidates, have thinner tubes. The sleeves move the weight up, balance forward, and increase the swing efforts; unless the owner spends money to have additional work done on them. That can be good or bad, depending on the handling "fingerprint" desired by the gun owner.
