At this point, I think I'll keep it.
I ran another quick 96-ish rounds through the k6 today; 50 148gr wadcutters, a few 158gr +P from Remington, and a bunch of different .357 loads: several cylinders of WWB 110gr, some Silvertip 145gr, and a cylinder each of Federal and Remington's old-school violent 125gr SJHP. Those 125s still flash, even with the lane lights on.
The 110gr was surprisingly mild, recoil-wise, and POI was perfectly centered, but about an inch low for me at 7. The wadcutters and 158+P both grouped a little to the right for me; I was prepared to believe it was shooter-induced, until I tried the silvertips and the 125 .357s; those were both centered, at the same distance. The full-power 125s grouped well--probably about as well as I can do these days, frankly. I wouldn't want to shoot a lot of either the 125s or the 145 silvertips. Recoil was, again, "surprisingly mild," but only because I was expecting borderline nightmare kick, from past J-frame and SP experience. Not pleasant at all, but certainly doable for a few cylinders, and probably on par with my 3" 65, despite the K-frame weight advantage.
So far, the firing pin still works.
One thing I've noticed: this thing heats up even more than I remember either SS J or K frames doing; that heavy 3" barrel was just hotter than hell by the time I got done.
Anyhoo, this is 6 of the 148 wadcutter (Freedom Munition's copper-coated), to the right of the 1" P-F square, and 6 Federal 125gr SJHP in/around the top left of the square.