I'd say thats good. Monitor FRP on the AP and see if its weird. But 500miss in 10 seconds is 50miss per second. If you measure that vs rpm thats a LOT of misfires.
Assuming is a spark miss:
800rpm idle = 800rev/60sec. 1 spark per every 2 complete revolutions, 400spark/60sec. 400/60 = 6.66666, 6.66 spark per second. 10 seconds should be 66.6 spark per cylinder.