ApparentlyWas I just under a rock?
BahahahaApparently
http://www.hkpro.com/forum/hk416-hk417-hq/136037-vltor-casv-416-rail.html
http://www.hkpro.com/forum/hk416-hk417-hq/143202-vltor-rail-systm-hk416.html
http://www.hkpro.com/forum/hk416-hk417-hq/149063-mr556-front-end.html
AND it's mentioned in a thread YOU started
http://www.hkpro.com/forum/hk416-hk417-hq/156878-mr556-rails.html
NOTE: all in good fun, Wolvee