Have played around with wax bullets out of my BlackHawk .41. Put a few bars of wax into an old cake pan and melted it. Just slid the brass into the wax after it cools but is still soft. The depth of the wax in the pan will dictate the length of the slug.
Great fun for sure and also work good for poping grackles under the bird feeder in the back yard. Even with "just" a primer, the bullet packs a lot of punch and after finding some of them mushroomed in such a way that Hornady would be jealous, I think they'd leave one heck of a welt if you got popped by one. They are loud, and the smoke from the primers will stink up the house.
On a wheel gun you may get primer setback that will bind up the rotation of the cylinder. I sure did in the BlackHawk. Heard that drilling out the flash hole will help with the problem, but never gave it a try as I sure didn't ever want to get one with an oversized flash hole mixed up with the brass on the reloading bench.
Think they'd work for fast draw practice if you're into that, but be very careful. The wax bullets aren't a toy, but would be much more forgiving if you wing your leg practising.
Quando omni flunkus moritati