Thanks to you all for the warm welcome.
Like I have mentioned, I'm so in love with this little 15-22. The
"phase II" is on the way, should be completed by Christmas. Hopefully, Santa will be super kind enough to make my dream come true. he he he.
Speaking of MBUS, fortunately, a gun shop (White Marsh Arms) in my area had a set in stock. It looks like the MBUS rear sight is kind of hard to find now a day.