[Uncle Buck]

I just realized I never answered the last part of your question.

1. How would you press in the plastic dome?

I use my single stage press. Of course you go easy, but I get them in with-out incident. My neighbor loads his with a Lee Hand Press.

They loaded like any other projectile.

2. How would you keep the shot in the dome to load them?

The capsule comes with a plastic base that is snaps into place once the shot is loaded.

I bought some and I think I was five plastic bases short. I called Speer and they sent me a whole new box of shot capsules.