Yah, if it is a pre-15 K-38 Combat Masterpiece, it is not really +P safe.
That isn't to say that you can't load it with +P for SD purposes. A few rounds of +P aren't going to hurt it (noticeably).
If you are going to use it for "social purposes", then if it were me, I'd shoot a cylinder (or 2) of your favorite +P fodder through it, just to see where it prints.
And then load it up with +P for "social purposes".
Practice with standard strength stuff. After all, .38 Spl +P just doesn't have all that much more pressure than the standard strength stuff. +P will beat it to death if you try and feed it with a steady diet of the stuff. But a cylinder to check it out and a cylinder for real isn't going to mangle the gun. After all, it is known (
) that they loaded factory ammo in the "old days" hotter than they do now.
Honestly, if it really were me, I'd brew up some handloads that used premium JHP bullets, got as much performance as I could, and yet stayed just inside of the top of the standard strength .38 Spl pressure limits. In this case, I think it is excusable since you are having to deal with an older weapon that isn't really intended for use with modern strength ammo. By artfully selecting your bullet and powder, I feel that you can get get performance that is similar to factory .38 Spl +P SD fodder and yet keep it within standard pressure limits.
One thing you might want to keep in mind is that .38 Spl +P 158 gr LSWC-HP SD ammo is designed for use in CCW revolvers that have barrels in the 2" range nowadays. But your revolver has a 4" barrel. Thus, you can get similar performance as a +P in a 2" barrel with standard pressure offerings in your 4" barrel, assuming you use similar bullets. You make up for the lack of pressure with the longer barrel. You can get the 158 gr LSWC-HP component bullets for reloading. Thus, you can brew up your standard pressure analogue if you reload.
