I cant give you a complete answer- but it looks like a prototype mechanism for a belt fed (or similar) automatic shotgun or grenade launcher or flare launcher?.
the shell rim locates in the grooves of the action, the drum rotates, bringing the chamber (with its barrel) rearwards over the shotgun shell and cocking the trigger mechanism at the rear of the action.
The shell fires, drum keeps rotating, moving the bolt forward, empty shell is ejected out one side of the action - while another live shell is moved into position.
Both look similar- but with slight differences- one probably an improvement on the earlier version.
Lithgow museum?
Just out of curiousity, I would love to have a play with these !
(Mark probably would too)
I'm with Mark, It's homo something.
It looks wrong, two homos holding an egg of some sort, possibly a baby or something spermy.
It's not natural whatever it is and the png should be banned!
Petermac33 and Japie stole the Illuminati eye from the top of the pyramid and are running away
(The Rothschild family, Bildeberger group, ancient egyptians, whole of the USA congress and all the world's reptilian-blooded Masons are chasing, but blend into the background are they are so white.)