Fremont,
You should go reread the dillon catalog,they advertise the 550-b with a loading rate of 500-600 rounds an hour,( pg 13,august,2001) and yes, it's quite possiable,I can do a 100 rounds in 10 mintues, as far as checking the powder, once the measure is set up where you want it it stays put, I usually check mine when I start and about halfway through, and on the last one, no, it doesen't take that long (I use a digital scale) with flake or ball powders the dillon powder measure works very well, usually does'nt vary by much more than 2-tenths, which is fine by me, You can use extruded powders as well,as long as the caliber you're using them in is larger than .30 cal, (smaller than that and the "sticks" get hung up in the powder funnel) But, shorter cut, extruded powders like varget, seem to work ok, 500 rounds an hour? Yes, you can do it!
[This message has been edited by Ralph (edited 08-19-2001).]