I cannot remember if I have shown these or not… (memory gettin’ worse, and my notes are scarce or lost).
I believe the large one is called the .500 “Whisper”, it is a cut down Weatherby cartridge, loaded with a standard .50 Browning projectile, meant to be silenced. I had a chance to shoot one about 15 years ago. The cartridge is 2.24"/57.2mm long, OAL is 3.69"/93.7mm.
The little cartridges are custom loads, made by a guy in Virginia [I do not remember his name] also about 15 or so years ago, made from .22 Hornet, turned down on a lathe. They are .22 caliber [cart = 1.05"/26.7mm, OAL = 1.38"/35.2mm] & .17 caliber [cart = 1.08"/27.4mm, OAL 1.39"/35.37mm].
And just for giggles, this is the penetrator core…