finally got a chance to put the 10 gauge together, shot some rem hevi shot 10ga 3.5" 1 7/8oz 6's at 40yds and put up 184 in the 10" with a Kicks GT .690, I was very happy with the results, all of the patterns had around 412 holes in the paper so that comes out to around 219 pellets per ounce, also it was only about 45 degrees out so i would expect to maybe move into the low 200's in warmer weather
i finally found a one piece mount that would work with the pre drilled holes so that i could use a red dot, i ended up using a ruger 10/22 mount made by weaver, the nef has two sets of two holes and the ruger mount matched up exactly with the front two of the holes, i was not sure it would hold well enough at first but i put 15 rounds through it and it was still rock solid so that was good enough for me