After some Filing on the Mounts it finally mounted firmly. Then it shoots great. I went with large tube, for quick acquisition. Tube is so large centering the dot can be an issue, when extreme accuracy is required. Power Switch is very tight, but will probably loosen.
Pros: Large bright clear fast
Cons: Mounts Sloppy, maybe too big for just Dot.
This review was written in the old system and had content requirements that are different than reviews written today.