OK, cleaned the carbine this morning, 50/50 ATF& kerosene, couple dry patches, done. Just normal powder residue. Accuracy with cast went to pot so I tried re heat treating coated 142gr PB (DT Smoke's red). Cooked for 1 hr @ 440F (not an exact temp) WD after cook and some had PC missing. Temp evidently got near 'slump' as exposed alloy has a case of pimples. Those beads of sweat that appear when you casting pot alloy just starts to melt. One had a strip 1/2 x 1/8 missing that was NOT found. IMHO coating split and contracted when cooled(?). It still passes smash and fingernail scrape fine.
Conclusion - can't damage the coating with over-temp or over-time cooking. Can't say the same for alloy.
2nd conclusion - cooking on a hot plate works for the PC but if you WD the temp is hard to control and get up to 400F. I'll re-treat these in the PID controlled oven.
Ian, I've been PCing for several years in rifle, my dirty target post and these results trying to show that PC doesn't really crud up the barrel and make it inaccurate. The 308W carbine hadn't been cleaned in a long time, shot with PCd cast for > year and still did near MOA @200, HV cast GCd. The BO uses HV PB PCd and should be worst case. I also don't see an effect of copper fouling from alternating cast/jacketed that everybody talks about.