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sscoyote
Optics Journeyman Joined: October/05/2004 Status: Offline Points: 327 
A buddy of mine has a permit for cow elk in CO. He's gonna use a 300 Win. Mag. with the 180 SGK @ 3075 fps mv. @ 11000 ft. elevation. He has a 624X Bushnell Banner (I believe that's the model) with a MilDot reticle on top. The mil system is calibrated for 9X. That means that the subtension of 1 mil @ that X should be 3.6 MOA. The rig is zeroed for 300 yds., which gives a CONSERVATIVE max. point blank range (MPBR) of 350 yds. for the avg. 20" cow elk lung area. If he adjusts the mag. to 18X he can use the mildot system as a MPBR rangefinder by bracketing the cow elk between 4 dots back to brisket, since 1 mil spacing now = 1/2x 3.6"= 1.8" @ 100 yds, and @ 350 yds. that 1mil space = 6.3". So 4 mil spacings = 4x 6.3"=25.2" the approximate distance back to brisket of a cow elk. Now if he has time he can adjust the scope to 18X, bracket the elk, and if it fits the 4 mil spacing or is bigger, just aim center mass and shoot. At his 18X 300 yd. zero his mil zeros were calculated by Exbal ( www.perrysystems.com )to be 380, 450, 525, 590, and 710 yds.(the distance between the 4th mil and top of post is 2X the normal mil spacing). Interpolation should be easy IF he also writes down the 1/2 way range between mil zeros (once we verify calcs at the range). I calculated his 10 mph wind drift by using a windage angle formula by dividing the mil spacing in inches @ each range into the wind drift at those ranges. This gives a windage reference in tenths of a mil spacing, and has worked as well as anything else i've ever tried so far.
Edited by sscoyote 
Steve
