Got back to the range today. With a 180 grain bullet, here's what happened:
7.7 grains of Winchester 630 - cycled 4 out of 5 (clise, but too light)
7.9 grains - every round (5) cycled,
8.1 grains - every round (5) cycled,
8.3 grains - every round (3) cycled
No signs of excessive pressure in any of the loads.
Thanks for all the info and advice!