Ok. . . . . The slide on your R9 is the early design machined from 17-4 ph stainless steel billets. The barrels are 416 stainless steel. We changed to machining both the slide and the barrels from 416 due to finding that the similar metals wore better than the two different metals, being 416 barrel and a 17-4 slide. We were using the best stainless we could find, however, as we progressed, we found the similar metals of 416 barrel & slide wore better for the longer haul. We also "beefed up" the slide by making the later generation slides slightly fatter. If you intend to carry it a lot and shoot it a little, you should be fine with it. I just wouldn't go putting hundreds of rounds through it like a Glock due to the fact that the R9s of the early generation were actually the smallest ones made and they got some "mid-life fat" added to them as we went along for better durability purposes. Overall, if the gun was keep nice and not shot too much, carry it and enjoy it.
Regards,
Eric C. Rohrbaugh