Dont know if this is even ok to post here so mods delete if not. Heres my thing everything i've read here suggests SDR-11 is THE tube diamater of choice for all consumer shells. I just got back from a "test" shoot and someone there was shooting out of an SDR-9 rack, the shells were Rambo's (cannister)and Double Impact (Double break peanut shells) by Beihei. The shells fit much snugger in the DR-9 but did not have to be forced at all and the height acheived by the burst charge was a good 40 feet higher (estimating obviously) out of the SDR-9 tubes vs the SDR-11. Also the cannisters fill all tubes tighter than ball shells and even more so than the multiple break shells which in general have a smaller diameter, I was actually dissappointed in the height of the double breaks out of the DR-11's. (Due to blow by) To further complicate this, i have repeatedly read that there is no noticable height from lift charge difference between 12" and 15" tubes, tonite i saw at least a 20' difference in height with same shells out of diffrent length tubes, both SDR-11, A little frustrated since i have just assembled 8 racks (200 tubes) all with DR-11 and most of them 12" in the last few weeks. If anyone else shoots out of DR-9 would like to here of problems, if any. Bottom line..... performance of SDR-9 15" tubes was night and day better than SDR-11 12" tubes. Comments please!