I could swear I saw this a while back - someone had made a 3-gun style shell caddy, but it had a stainless steel spring in it that would help retain any rounds if you were to load only some rounds instead of the whole caddy, as opposed to the original caddy where if you take only one or two the rest of the shells are flying loose everywhere.
Anyone know which one I'm thinking of? I can't seem to google my way back to it.