Well it took 2 months, but we finally took the 500 for a test run. It ain't all that bad!?
As far as recoil goes.
We fired some test loads using lil gun and the 2 HP configurations, and the solid. 26.0-26.5 and 27.0 in all three meant we would have to fire 45 rounds to complete the test. We got "tired" only fired half. SIL had brought some HSM loads along, 350 HP. They were like shooting medium 44 mag loads.
I found out that the top load of lil gun,(27.0),in the solid @ 695 grains will have to be pulled apart. The 26.5 had really flat primers, pressure was max right there. I may even drop them back to 26.0
Accuracy was excellent. Offhand standing @ 25 yards, we were keeping them in a 4" group. Group was a bit high, about 4" from where he had it set for the lighter bullets. We then backed up to 50 yds, tried some more of the solids. They were even higher. Shot right over the target until we started to aim at the bottom edge.
One concern from some has been "will those huge chunk O lead stabilize"? YES!
Even from 50 yds, the boolits were hitting point first, cutting nice clean holes.
No chrono data, it was misting and not real warm. I'll drag it out the next time I take it shooting. We tried to dig one of the penta points out of the dirt, 6" in, still no boolit. It's gonna take a lot of earth to stop one.