Ballistic products dot com has all their 410 wads in stock.
You can cut down shotgun shells.
Going a pinch lighter with shot won't hurt anything.
Cheddite primers are great, they're about 1 thousands bigger than domestic US 209s.
Try to use Win, rem, fed 209s for your first and second loads and use the cheddites on shells where the primers get lose to get one or 2 more loads out of a hull.