Some one may have alread thought of this. I found this works with sizing bullets i take the breech lock bushing and screw it in on the under side, then attach pvc clear tube.The boolits slide on on down. it does not seem to need secured on a pretty good fit.
https://leeprecision.com/spline-driv...-lock-bushing/
https://www.homedepot.com/p/Everbilt...C015/303124993