George,

My feeder is very slow with 600 too-throws it in a great pattern, and very far, but I have mine set at 10, 8, and 12 seconds right now and it's used about a third of a bag in three weeks. The AM 600 is at the top of the sizes the feeder can handle-the Silver Cup 9.5mm pellets I tried in mine simply wouldn't fit from the bin to the throwing mechanism, and they're only a fraction bigger than the 600-they're almost identical in hand.

That said, I've never had a jam in the TH when using 600, just had to set the timer for a longer time. My Aquapro jammed regularly when I used 600 in it.