Welcome to the forum.
About the only advantage these bullet style pellets have is that they penetrate really well - thanks to the solid nose and the heavy weight for their diameter.
The original Sheridan Bantam pellet suffered at times from yawing en route to the target - the head of the pellet being smaller in diameter than the tail allowed the pellet to skew as it came out of the barrel. My own experiments with some Bantams of unknown vintage show rifling marks on only one side of the pellets front end. And indeed from time to time they do yaw. Yrrah here has some video footage of the phenomenon.
The H+N's above are fully engraved by the bore - they are not too bad accuracy wise, though they prefer to be driven harder as opposed to softer. At $10 for 500 they were too good to pass up and I use them for plinking. That said, I shot some Indian myna birds with the cylinders and on five pumps they knifed right through the birds.

There's a certain nostalgia to firing cylinders from a Sheridan.
If I want accuracy I'll reach for the Beeman Kodiaks or the JSB Exacts. I think the Kodiak will be my go to pellet if / when I decide to shoot a rabbit or two with the Sheridan.
From what I gather from US forums, the Benjamin .20 semi waisted cylindricals are not all that good in quality anymore. I have never seen them anywhere Down Under.