My guess is the first generation of them had a different spring in them. Retailers such as WGC and UNC probably just haven't updated the specs on the web yet.
Crunchmeister did a review on ASC here awhile back and his was in the 300 FPS range.
Here it is: https://secure.airsoftcanada.com/showthread.php?t=52250
I received my Real Swords in March and June of 2009. They must be later models with a stronger spring. Pretty sure the 56-1 was from WGC.
One this about the RS's is that the hop rubber must be very hard. I've adjusted it so the hop up works decent enough with Madbull .25's or .28's just fine. Mind you, my CYMA M1A1 outranges both of my RS's and all of my other AEG's. And that's just effing wierd eh.
I was planning on changing the hop up on both but I have been a chairsofter the last few months so that project is on hold indefinitely.
Hope this helps.