I picked up one of these from SARCO

MSR219 MK10 MSR 1 Fixed 2 Folding Leaf Express Sight (round bottom) 3/$138.95 $49.95

MSR221 MK10 MSR 3 Folding Leaf Express Sight (round bottom) 3/$138.95 $49.95
http://www.sarcoinc.com/mauser.html

You might want to read this thread -
http://forums.nitroexpress.com/showflat....p;vc=1&nt=2