Gf1 , hell 9's bridge in my 410 600jr. You have to tap the drop tube for all sizes of shot with 410's. Last week I bought a used 600 jr in 28 ga from a friend. Right now I don't have a 28 but sooner or later one will come along. The eagle 7's are going to be used thru that 3/4 oz bar to see how much it throws. The MEC tech guy says the bars are all calibrated to drop their marked weight with 7-8 shot. With 7's I hope it will be around 11/16 oz.. 11/16 oz is the std charge on 3" 410's. Through ballistic products I ordered a 410 short kit and some 410 nitro cards the other day. 11/16 oz is 205 number 7's which should make a better pattern than 152 #6's. Bunch of guys swear by 7's so I'll try them. I don't much care for adj bars they seem damn sloppy to me..mb
MB, in .410 on my MEC Grabber, #8.5 does not bridge, but #8 sure does. As such I stick with #8.5s; I only load 2 1/2” shells. I have a small stash of factory 3” shells in somewhat larger sizes for hunting, although I only use the .410, a Model 42, for preserve birds.
I also agree with you 100% on adjustable charge bars, which I consider to be an accident looking for a place to happen. I will also admit that I don’t check the weight of the shot charges, and am certain that with high antimony shot the charges of shot are light. I just shoot ‘em; birds fall and clays break.