Originally Posted by phildenton
I would contact smith & wesson directly. Aside from that stick to what is stamped on the barrel.
What he said--^--
What proof steel they use today may not be anything like they used 40 years ago.
I reloaded some pretty hot loads for my pre '70's version K38, probably more like +P+, and it seemed to handle it okay, but got to thinking that the accuracy didn't improve, and I was beating up a pretty nice gun just to get some extra feet per second out of it. If you want that kind of performance, trade it for a 357 Mag.
Unfortunately, I lost the K38 to some sticky fingers.
Mod 14-2 8 3/8 bbl SN-93895