3000 lb barrel 48" ODx 32" long; two 4" wide bands welded to od of barrel which are 1/2" thick; so, band OD is 49". Barrel (band actually) rests on (2) 3" diameter shafts; one shaft drives system; other shaft idles. shafts are steel, bands are steel. So, there is 8 linear inch per shaft of contact.
system is exactly like a small rock tumber except steel on steel contact. Surface finish of the shaft and bands would be 125 uf.
It's been a while since I've calculated this; wanting help.