As Winny Fan already mentioned, it's simply a 222 (not the 222 Mag) necked down to .204. I'm guessing the 204 Ruger, 20 Tac, and 20 Prac will all shoot 100-100+ fps faster than the 20-222. It's no particular speed demon per say but I already have a 204 Ruger and a 20-250 so I've got the 20 cal speed demon cartridges covered.
With this build I wanted a fun little cartridge that didn't need a lot of barrel length and I've been wanting to do a build that had more of an old school look to it so this one when it's all done will have a traditional Rem 700 BDL Custom Deluxe look with the exception of all the metal will be Cerakoted black instead of the classic bluing.
There are quite a few "improved" variants of the 20-222 out there, and they all seem to shoot very well, but I'm not looking for yet another cartridge I have to fireform for so I am lazying out on this one and sticking with just the straight 20-222.