I used this ballistic calculator [url]http://www.beartoothbullets.com/rescources/calculators/balistics/[/url] to calculate bullet drop/rise using a 55 gr FMJ bullet with a BC of 0.255, muzzle velocity of 3240 fps, and sight height of 2.6".
With a 25-yd zero, you get the following:
00 yds, -2.6"
25 yds, 0"
50 yds, +2.4"
75 yds, +4.5"
100 yds, +6.4"
125 yds, +8.1"
... ...
250 yds, +11.5"
... ...
414 yds, 0"
I just attended a CQB carbine class where we zeroed at 30 yds. The bullet would be +1.6" at 50 yds, +4.8" at 100 yds, +7.9" at 220 yds, and back to far zero at 364 yds.
The [url=http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw]improved battlesight zero (IBSZ)[/url] gives a near zero of 50 yds and a far zero of 243 yds, with no more than -2.6" (muzzle) or +2.3" (150 yds) between these ranges.
My question: Is there a different zeroing method for CQB weapons (100 yds or less)?