One thing I would change for the dimensional specs on an 11.5” heavy barrel would be using 5/8x24 threads vs 1/2x28. It’s a big step down in mass when you want the benefits of a heavy barrel that is heat-tolerant, that you are sacrificing extra weight in-favor of better grouping at reasonable distances.
A tight-fit muzzle device and suppressor will mitigate that a bit, but I still don’t like such a dramatic change in barrel profile with the step down to such a small threaded muzzle. It’s just begging to absorb a lot of the heat load and bell out. Chrome-lining and CMV steel help counter that, but any advantage would be good in that area.
For gassing, you can choke the flow of a large port back at the carrier with a Bootleg. Instead of going to heavier buffers, try extra power spring weight in the action spring. I use standard buffers and extra power springs more now, after feeling and seeing how well that manages the cyclic rate.