I've been shooting some ACOG optics at the actual ranges indicated on the BDC (it's important to remember that these are meters). At the altitudes I shoot at, the longer range marks are off significantly, but it is possble to find factory loads that match pretty well. Of course, handloads can also be calibrated to match to some extent.



Anyway, I wanted to know more about the reticle, and there is a lot of contradictory info out there. I thought I'd measure for myself.



I took a yardstick and wrapped electrical tape every inch to increase contrast. Every five inches had different color tape, to make counting easier.



I placed this stick at 100yds, measured by the laser rangefinder. Here are my results fir the inches subtended by each BDC mark from the 100m mark. Numbers are to the nearest .25"



4x32 NSNTA01



100m 0"

200m 1.75"

300m 4.75"

400m 8.5"

500m 13.25"

600m 19.75"



3x32 TA33R8 - .223



100m 0"

200m 1.75"

300m 4.25" - Difficult to measure, since it's just the end of a line

400m 8.5"

500m 13.25"

600m 19.75"



One inverse tangent later, we obtain the drop angles (in minutes) from 100m, to the nearest .25'



4x32 NSNTA01



100m 0"

200m 1.75'

300m 4.5'

400m 8.0'

500m 12.5'

600m 19.0'



3x32 TA33R8 - .223



100m 0"

200m 1.75'

300m 4.0'

400m 8.0'

500m 12.5'

600m 19.0'



I used a 3x magnifier behind the ACOGs, which made things a lot easier. Of course this will magnify the image and the reticle equally, if there is no parallax. Acog parallax at 100m is pretty minor.



On the 4x I tried the measurements without the 3x magnifier. I could only get the 600m measurement, and it came out 20" +- .5 So the 3x magnifier doesn't seem to be an issue.



Edited : typos corrected in 300m data

Sorry, double post.