I've generally inserted a couple 20 ga over shot card wads,
under the shot in the 10 ga shot cup
Ive used a mec reloader and shoot an ithaca 10 ga
https://www.midwayusa.com/product/1013168287

https://www.ballisticproducts.com/PT...nfo/222PT1044/

https://www.ballisticproducts.com/10...s/products/84/

https://possibleshop.com/s-s-wads-shotgun.html

https://www.trackofthewolf.com/List/Item.aspx/170/1

https://www.precisionreloading.com/c...!ga=10%20Gauge