NYKENN;
Found one of ur questions on an old post. It is a good one.
Since l have made and sold some to members of forum, will try to answer
Started as a method of saving powder when time came to change/empty powder.
Realy goofed up on first go around. Then the idea of no powder being left between the powder slide bar and bottom of powder magazine,became a question. It had to removed by what ever method available. Then the question of the slotted screws holding the housing down,becoming worn by a sloppy screwdriver being repeatedly used. The changing of powder slides can be done without removing top of housing. When only the amount of powder needs to be changed,like 2.7 grs wadcutters to 3.5 round nose .38,s. Use 10/32 allenheads instead.
Safety factor; possibly no powder. That l leave up to the loader. with or without drain ; his/her problem.
Convenience; It can be a drain or a cutoff, by inserting a plug in drain tube, remove when putting powder back in container.
Simplisity in use and construction was my main objective.
Cost is another .
Have tried to attach pictures to this forum, but that is one point where l,m stumped
regards; maurilew (Ma)