u/Certain-Leg-7371

I've tumble stage #1 60/90 grit twice now. The barrel empty weighs 7.4lbs, 3/4 full of rocks it weighs roughly 16lbs. That's 8.6lbs of rocks I'm tumbling. Unless my scale is off!! So I use 9 tablespoons of 60/90. This is a 7 day cycle. It's grinding slower than my 3lb barrels would in 7 days. It's advertised as being a 15-17lb capacity tumbler. It physically won't hold 15 pounds of stones!!! What am I missing here. Also it's bruising rocks. Should I use ceramic media on stage one with this tumbler to cut down on the bruising? Am I not filling the barrel full enough? I'm not tumbling anything over 2" and the smallest being 3/4-1" all roughly 7 on the mohs scale. Jasper, agate, and quartz. I'm treating this barrel just like I would my 3lb barrels that I have great success with. I'm just tumbling some slightly larger specimens, and I'm not doing something right. Any help would be much appreciated.