The smith's comment was more that the older 742's will NOT take the abuse of EVERYDAY shooting. Hunting situations it will last along time!
He gave you good advice, but a box of ammo a year will not wear it out anytime soon!! We've had several of them here, and only one actually got close to being wore out. That was the one dad fired nearly every day for practise, and it had at leastcouple thousand rounds through it, most of wich were handloads. I also suspect they were "heavy" loads too...
DM