That is a rail, just not a standard one. You can get an adapter at Condors Flight or Your Gun Parts for $20 bucks or so that will let you mount a Weaver or Picatinny accessory.
I'll leave the "Why?" for someone else.
![Smile [:)]](/emoticons/emotion-1.gif)
Edit: Here's a link and the price went down too.
Junk Hanger Yes, it will fit the UC and Mini too.
By now your name and particulars have been fed into every laptop, desktop, mainframe and supermarket scanner that collectively make up the global information conspiracy, otherwise known as "The Beast." - Dale