.300 whisper ar upper info

[febisfebi]

I have been somewhat interested in this, but i havent been able to fine out much info about it that I was looking for.
so far i know that both oly arms and model1 sales sell these, as well as a company called ssk, which also sells many other cal's.
So what i'd like to know, is how this round performs, and how practical it is on an ar. especially if someone can compare it to other 30 cal rounds such as .308, .300wsm etc. And although from picture comparisons the cartriges seem similar in diameter and lenghth of a 223, but a much larger bullet, does one need special magazines to fire this round? if so, where are they available. any other info would be great, as this certainly is something of interest.
does anyone own one of these, or have used one of these, and can comment on it?
thanks
edit: looks like SSK industries invented the cartrige

[rodent]

its a .221 fireball necked up to take a 30 caliber bullet.does not need spacial mags.as far as how it compares to the .308 and 300wsm its nowhere near as powerfull,its closer to a 30-30.cor-bon sells factory ammo and most new reloading books have reloading spec's.after the first of the year i'm building one on a RR US property lower.i'll mostly use it for deer and hogs.here (http://www.quarterbore.com/300whisper/links.html) is a good page of 300 whisper links