BH50-

Thanks for sharing your experience with that little lyman slug on deer. I appreciate the comments.

I don't think this is much of a step off the original topic, as at some time someone will find this thread in a web search, open the nitroexpress site, and see the wide range of experience the members here have with different kinds of guns and rifles which are so elementally similar.
That person might even be fiddling with that 20 gauge lyman mould thinking of setting up to run those little gems in their old small size bore rifle! There are a a few more of these old special time capsules out there waiting to be found, tuned up, and taken to the field - their owners without the original mould or quite the idea of what to do about projectiles
I know I've done such searches.
That's how I found this place nearly three years ago.
This kind of pleasant latitude in conversation brings the knowledge into the meeting place - and I very much appreciate your nudge to get us back on focus to the old bore rifles the original poster was asking about.

Also to note, I'm quite happy for you that the rifle you made for yourself has been a successful tool in the field. That same random person searching the web *might/might not* have the confidence to get out there and hunt with it.
Perhaps this cross-functional yet very similar experience will be enough for them to get out there and work that rifle and their skills up to the point where they'll be competent and comfortable enough to go hunt with it.
That's a victory in my books!

Couple more questions for you on that deer kill.
Do you have an estimate of the impact velocity?
Did you find parts of the slug in the animal?

--Tinker