Well, I did what I threatened to do back in post #2,112; just finished putting together a "Rockslide Special."
Karl at Kampfeld Customs cut the barrel to 18" and threaded it. Check out the close-ups of his work. I can't believe how tidy the blending is from the barrel to the adapter (1/2-28 to 5/8-24). He such a good guy to work with. I couldn't be happier.
The pics show the rifle mocked up/dry fit. I still need to install a 1/2" LOP spacers, attach the comb risers, then degrease, clean, and torque everything. Looking forward to getting it zeroed and shooting some drills. I got 7 cases of Hornady Frontier 68gr BTHP Match to feed this rifle, so hopefully it shoots them halfway well.