I believe I heard 9/16 or maybe 19gram loads. NOT 14.
I heard it in one of the videos related to the open championship.

Different country, different rules.

3” loads add quite a few targets to a round of clays in the .410

I would estimate 10 for me on a 100 round course.

If you notice how British sporting clays are often shot, you will see stations where you bang out eight identical shots before moving on. That is death to a 410 at the edge of range.

Out there doing it best I can.