They are but the USMC first conducts the 36 yard zero and confirms at 100 to make final adjustments for the RCO.
For rifles, typically BDC scopes, which are based on a 100 meter zero getting it on paper closer definitely makes sense. However I would submit that isn’t using whatever arbitrary range as a zero. You are using that 25, 29, 36, 50 meter zero to get on paper for the 100 meter zero. For that using whatever range is closest in the ballistic arc to 100 meters makes sense but it’s still a 100 meter zero.
For rifles, typically BDC scopes, which are based on a 100 meter zero getting it on paper closer definitely makes sense. However I would submit that isn’t using whatever arbitrary range as a zero. You are using that 25, 29, 36, 50 meter zero to get on paper for the 100 meter zero. For that using whatever range is closest in the ballistic arc to 100 meters makes sense but it’s still a 100 meter zero.
USMC 36/300 yard zero predates the ACOG by many, many years.
Here is some info (Lt Col Blish) https://robarguns.com/blog/2013/11/24/battle-sight-zero-bzo-who-has-it-right/
Point blank range caculator
http://www.shooterscalculator.com/point-blank-range.php?df=G1&bc=0.105&vi=1070&sh=1.5&ts=1.
I don't have access to it at work but I believe you can include MPBR on Shooters calculator when generating drop chart and table
That's a fine article, and Freddie Blish is a good dude. However, much of the info in that article applies not only to iron sights, but some particular iron sights.USMC 36/300 yard zero predates the ACOG by many, many years.
Here is some info (Lt Col Blish) https://robarguns.com/blog/2013/11/24/battle-sight-zero-bzo-who-has-it-right/