I have played with some .222 brass. ( Necking it up to .243, .257 and .264) It makes up a cool looking little round.
A few years back I had T/C Contender made up with a 25-35 Win. barrel. Killed two bucks with the Barnes 85 X-bullet and the original 90 gr. Barnes SP at around 2,600 fps. Worked as well as any other cartridge. Range was inside 100 yards.

I'm wishing Remington would hurry up with the 6.8 SPC