Howdy folks. A quick question about cylinders. Alright, I just picked-up a pump and cylinder to try a couple of days ago. I'm 6" in girth and got a 2" tube. The problem is the tube has a bit narrower ring at the inside base of the tube, and man, that little edge felt like a pair of pruning shears after a few minutes. So out came the dremel tool and I ground that edge away. The question is, do all tubes have this inner ring as part of the tube?