http://www.youtube.com/watch?v=ex8dSp_DJQA
A video which shows use of the duplex reticule as a BDC, along with confirming our Home Range experience that, at 500 yards, the .22 rimfire has flat "run out of steam" and pretty much useless - we never could get it to even 'group' at 500. The shooters in the video stated 6-7 hits out of 100 shots from sandbags, with a spotter to adjust their shots.
Target was an 18-inch round plate, pretty close to our standard 20-inch target. Mention was made of a 90 minute holdover from a 50-yard zero...
http://www.youtube.com/watch?v=yCU9012I84k
Same guys, at 300 yards, not as much info (could have given holdover, for example) but regularly without much trouble ringing a 13-inch round plate. An experienced British competitive target shooter suggested, way back in 1940, after field testing, that a .22 rimfire would make an effecctive last-ditch military weapon out at 300 yards.