James,
Blimey you must be good! You'd have to be going some to knacker a barrel in fours years shooting Prone/3-P; Anschutz reckon their barrels are good for 100,000 rounds, with some lasting longer, and some a little less. Unless a four year old barrel has been owned by a very serious shooter, or bulged, or cleaned with a rusty coat hanger and battery acid, I'd expect it to have a good amount of life left, at least by my standards.
I know of early-production 1813s that are still producing competitive scores at county level, although others of the same vintage have given up the ghost, to be replaced by a Border/Maddco/Lilja etc.
Huey,
that's quite right, although as the 1813 was produced for a fairly short space of time, you have a good enough idea. Now with a 1913 the exact age is more important, the barrel could be 1987 or 2017. This is assuming the seller knows what they have. That's not an issue here, but some owners think everything is a 1913.