If your having bridging problems on your shot drops? Try running a bunch of pipe cleaners down the drop tube. You'll need more for the 28 ga. than for the 410 bore of course. Just use, as many as you get down the tube at one time. This will fix your bridging problems PDQ.
As far as shot goes. I prefer to use #8 1/2 shot. Shooting the little gun at night under the lights. The handful of us, who shot the baby bore saw dust on targets very clearly. We came to realize we were hitting the target with one piece of shot. We were all using Law. Brand Mag shot as well. We all switched to 8 1/2 Law. Mag shot and most of the dusting stopped real quick. We all have been using 8 1/2 shot since that time. I also love using 8 1/2's for all my 16 yard single shots, & the first shot of doubles as well. I also use 8 1/2 shot for my close work in Sporting Clays as well. Of course use what-ever size you have laying around before you go buy a special size of shot just for skeet. Both 8 1/2's and 9's will work just fine for skeet. Even 8's will work in a pinch with the smaller bores. break em all jeff