Situation update,
I went back with the same load and components in my Model 66-3, this time I took extra care and attention to REALLY scrub out the carbon rings from my .38 special loads I test in that gun, and I have to say, great success.
The cases come tumbling out with just the SLIGHTEST touch of the ejector rod, and only after around 100 rounds or so did the cases start to develop a slight bit more stickyness.
A 50 round group averaged around 1170 fps from my 4 inch barrel with 12.8 grains of Accurate #9 under a 158 grain JHP, standard CCI 500 primers seem fine, though some are a bit pancaked, most are rounded. I even tested my favorite 12.6 grain load with a 158 grain bullet, and that was a bit dirtier, and did cause a slight bit more stickiness than my 12.8 grain loads, but I can safely say that yes, stickiness in extraction can be a good indicator of pressure.
A 13.5 grain load was also quite fine, they were a bit sticky, which falls in line with the 13.8 grain max load for AA#9 under a 158 grain JHP round.
Picked up H110, used a CCI 550 with a medium crimp, around 15.8 grains under a 158 grain JHP, did about 1070 fps avg, sd of about 50. Honestly not a bad load for plinking, a bit of unburnt powder though. Pretty accurate at 10 yards in double action. Will try 16-16.3 grain next time.