I'm not disputing your maths as I know nothing about it, but if a pellet can barely cover 50/60 yards on a trajectory, I just can't see it would go over twice that distance vertically.
seriously get chairgun.... (theres no dimentional porthole for the pellets to vanish into lol...its up to hundreds plural of yards at the right angle like...)
a link http://www.hawkeoptics.com/chairgun.html
persavere a bit with it you'll get it, then check out the ranges, i personaly take rabbits to a 65 max, but the odd one creeps in at the 70 mark where its totaly at its killing lowest....on a good day like. and you can exspect a shit load more than 40 meters btw...eeeek..woodies at the 140 mark arnt hard...the problem is the retaing the 4fp's yu need to kill it (well bit less on a woody with the right pellet etc etc etc).