I had the job of changing out this barrel on an Officer's Model Colt .38 a few years ago; kinda interesting. After I slabbed off the side out of curiosity, the next morning there were raised bumps on the exposed lead cores from compressed air trapped in the hollowpoints! I never did find out who did it; the revolver was purchased at auction by a friend. My only charge to him was that I got to keep the barrel.
Just Damn! If you don't see holes in the target, maybe you should stop firing to figure it out. I've stuck a couple of bullets in barrels over the years, but I've never stacked them like that.
Tip of the hat to The Guncounter Forum.