I always wonder about the mental health of people who go to extremes to get a powder bushing to drop some exact amount. You might consider that you can't. And even if you could it would be an exercise in anality. You can't get it throw to throw, you can't get it from the top of the can to the bottom, and you can't get it lot to lot.
If you have any loader you can easily afford the series of bushings around your normal load requirement. In there somewhere will be two that will be just too light and just too heavy. Use the light one. How difficult is that?
IT'S A SHOTGUN! - - - get over it
I use a 366 and before they were generally available I made an adapter for MEC powder bushing. Over a couple mo worth of gun shows I accumulated one of every MEC powder bushing. Buying a couple or more at a time they cost me less than $1/each. BFD. I've never used most of them but who GAF? I have several presses so I did get dupes of ones I use a lot JIC.
Only JMO but I would never have an adjustable powder drop. Adjustable things can adjust themselves. I have no faith in their good will. If changing powder bushings is so daily an event that an adjustable bar is felt necessary maybe you should get a couple more presses.
