Pellet sizer

https://www.trrobb.com/product/adjustable-pellet-seaterv1

Screenshot 2023-10-09 08.48.21.png
 
That's the one I was going to recommend. I have one in 22. In my experience it does require some breaking in. Like you need to build up a layer of lead in it like you would most airgun barrels
Agreed, a little "sticky" at first. Once set where you want it, very consistent & easy to use.

.20 is available in the size dropdown list, but believe .20 & .25 are made to order.