I don’t know of any; covet away! It’s a s-w-e-e-t firearm, and so is my Beowulf .50cal & ACOG, for “shorter-range wet-work”:
http://www.shopalexanderarms.com/Products-.50_Beowulf.html
and
http://www.militarywarfighter.com/Trijicon_TA64850_p/trijicon-ta648-50.htm