Also, does the Dillon have a "powder baffle" as an accessory? If that's in place I assume it needs to be removed in order to pour out all the powder?
The Dillon powder resevoir has a small baffle molded into at the bottom. It covers the metering cavity.
I do not think they offer a sheet metal baffle similar to those offered by Redding, RCBS, et al but if you want one, it is easy to make.
There is a web page with dimensions for different diameters hoppers. The metal can be obtained from an empty aluminum drink can.
Or, if you have access to a CAD program, the baffles are basically an ellipse that are bent in the middle to make it a hat section. The cad program can provid a template for cutting the baffle. The major axis of the ellipse should be about 1.4 times the length of the minor axis which would allow you to bend the baffle at about 90 degrees. Note, the minor axis is the inside diameter of the powder measure hopper.
When dumping powder from the powder measure, depending on the fit of the baffle will depend on whether I remove it. The baffle in my Redding powder measure is held in place pretty well by the tension of the baffle so I do not remove it. I pour out as much powder as I can through the holes in the baffle and then cycle the powder measure to the remaining out the discharge of the powder measure.
My Uniflow has a loose fitting baffle which will slide out with the powder as I am dumping it. So, I pour carefully into a funnel. The funnel catches the baffle and directs the powder back into the powder jug. I still cycle the powder measure after the bulk of the powder has been removed to get the last of it out of the discharge chute.
The Redding baffle is bent so that it presses against the side of the hopper and allows for placement anywhere in the hopper. The loose fitting Uniflow measure just sits in the bottom of the hopper. I could reduce some of the angle of the hat section of the Uniflow baffle and would then grip the sides of the hopper.
As a side note, the holes in the baffle that allow powder to pass to the metering section should be placed so that they are not directly over the metering cavity.
As Hondo 60 said, the hopper can discolor fairly quickly even if you dump the powder at the end of each reloading session. Leaving the powder in the powder measure for an extended time, and overnight is an extended time, just accelerates the process.
Some folks take clear plastic sheet protectors and cut the to fit inside the hopper. This provides a disposable liner that can be changed when it discolors. It is more trouble than it is worth in my opinion but I have some other reloading idiosyncrasies so who am I to judge on the merit of the sheet protector liner.