Nice work Ian, I am duly impressed. I may even try it some day. I need to start at the beginning and read all of your posts on this to see your technique and equipment used.
I forgot a few things in the "lessons learned" list. This isn't holy writ but my experience from my own data points so far.
One important thing seems to be the bullet having displacement grooves of some kind to prevent fouling accumulation from the coating. I have never actually tried "slicks" or grooveless bullets coated, but Bama has done a lot of work with them and has battled fouling akin to copper jacket fouling in his bores. I have never had such fouling from my traditionally grooved or micro-grooved bullets. Intuition and lessons taught us by Frank Barnes seem to hold true for all monolithic bullets, even paper-patched high-velocity bullets.
Another important point for loading HV powder-coated bullets is diameter. Typically they shoot best for me when sized somewhere in between the nominal groove diameter and what works well for traditional lubricated cast bullets in the same rifle. In other words, never go larger than throat entrance diameter due to scraping off the coating going into the throat. Often (in my experience with just a few rifles so far) sizing the driving bands for a light scuff-fit in the throat or even a bit smaller depending on throat geometry gives the best accuracy. Bolt-actions with some parallel freebore benefit from a more snug fit and semi-autos with funnel throats from a slightly more loose fit. In all cases, selecting and sizing a bullet for minimum deformation and engraving force until the gas check begins entering the throat has given me the best results. Powder burn rate, crimp, neck tension, and bullet jump all need to be adjusted for the low engraving pressure to yield consistent burn (note how well the fast-burning Reloder 7 worked for my .308s at 50K psi and over 2500fps, not something that would do well with traditional cast bullets and certainly not with copper jacketed!)
Other techniques I use that seem to help are seating the gas checks Lyman-style in an old 45 luber and then push-through presizing the bullets to crimp the checks and reduce the amount of metal moved during post-coating sizing. Coating after applying and crimping checks seems to help check retention and allows the checks to be annealed in the oven (for better or worse?). The only drawback to coating the checks is uneven powder coat on the bullet bases which I believe in some instances degrades accuracy. The bases could be wiped before standing to bake, or other techniques used. Most anything added or refined in my methods would be chasing sub-moa, and my LR-308 has shown repeated sub-moa tendencies without doing anything special like weight-sorting bullets, flash-hole prep, weighing each powder charge, or any other exotic loading routines. Most of my ammo is loaded on a Lee turret press with charges thrown from an RCBS Uniflow straight into the cases.