Improved Battlesight Zero [IBSZ] by Lieutenant Colonel Chuck Santose, US Army (ret.)
Lt. Col. Santose’s military experience includes 12 months of combat in Vietnam as a Ranger, and 29 distinguished years as a trainer as well as an infantry and armored unit commander. His IBSZ technique has been quoted by former Navy SEAL Jeff Gonzales in his book “Combative Fundamentals, an Unconventional Approach” (Trident Concepts Research Group)
http://www.tridentconcepts.com. IBSZ is in private use in 101st Airborne Division, 82d Airborne Division, and several SOF units. Official Army/Marine Corps doctrine ignores the IBSZ technique at present. I have contacted Lt. Cot. Santose and reprint his guide here with his permission. He mentioned in his e-mail to me that he gets e-mails a couple of times a month from users in SW Asia telling him how well it works.
After reading this article, everything will make sense. The math does not add up to shoot at targets closer than 300 meters with the unmarked aperture. When zeroing in the Marines we used a 36-yard zeroing target (I know the manual says 25 but that’s not how we did it), the unmarked aperture, and had our rear sight elevation set two clicks below “8/3.” This article below explains everything, and I have adjusted the rear sight elevation knob on my AR such that it is set to “6/3” -4 (four clicks instead of two because my AR uses half clicks).
The text that follows was copied from:
http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw By Lt. Col. Chuck Santose
1. Current Army/Marine Corps battlesight zero and its procedures are well described in TM9-1005-319-10, the M16/M4 operator’s manual. A recent copy of this manual is available at AR15.com. Procedures in the manual will not be repeated here.
2. The current 300 meter battlesight zero is a function of the sights on the rifle and I personally find it shoots too high for the vast majority of combat targets, including the Army’s qualification ranges. The procedure listed here take better advantage of the flat trajectory of these rifles as well as the use of civilian ranges, which are seldom surveyed in meters.
3. When zeroed at 200 meters, a distance twice that of normal combat engagements, these rifles have a very flat trajectory that is less then 2” from line of sight at all intermediate distances; a distance that’s smaller than the normal dispersion of arsenal or factory loaded ammunition. This tiny trajectory arc allows very precise shooting out to 250 meters where the bullet is only 2” below line of sight.
4. A 200 meter zero has the happy coincidence of an initial trajectory cross-over at 50 yards, a distance available on almost all civilian ranges including many indoor ranges. This makes it easy to achieve a 200 meter battlesight zero without recourse to surveying your own range. If 200 meters is available you can fine-tune the zero at the real distance. You should when you get the chance.
5. The lowest sight setting, however, on these sights is 300 meters so the sight needs to be modified to preserve the markings on the sight (despite the fact that no one ever sets a range on these in the real world other than a USMC range). The sight needs to be set to bottom out at 8/3 -2 clicks. This will be the new 200-meter setting.
1. Flip the rear sight back to the unmarked aperture. This will reveal a hole in the top of the handle.
2. Rotate the sight wheel all the way down. It will probably be exactly at 8/3 (6/3). Don’t force it down.
3. Using a 1/16” Allen wrench, loosen the screw (under the revealed hole) in the sight wheel 3 full turns. Leave the wrench in the screw.
4. Rotate the bottom half of the sight wheel two clicks clockwise. This will raise the sight body if you look at it while you’re turning it.
5. Tighten the Allen screw, remove the wrench, and confirm the sight bottoms out at 2 clicks BELOW 8/3. If not repeat the procedure until it is right.
6. Battlesight the rifle per the -10 with the following exceptions:
1. Sight should be at 8/3 -2 clicks, that is, all the way down, not up a click. Please note removable handle sights are marked 6/3 (rather than 8/3); also some are in ‘half-clicks’ as well. There should be 3 clicks between 3 and 4 on the knob. If there are 6 clicks then the sight needs to be set at -4 clicks (instead of -2).
2. Small aperture, nose to firing handle weld.
3. Distance is 50 yards.
4. Point of aim should be point of impact of bullet.
7. Remember you’re adjusting the FRONT SIGHT for elevation, not the rear, and that each click is about 1/2” (actually a little more) at 50 yards. You won’t get it closer than that. Don’t frustrate yourself trying.
8. You’re done. Leave the sight in this position for 99% of your shooting.
9. If you have to shoot targets you KNOW are 300 meters away or more, just click to the right number on the sight
10. If you’re patrolling set the sight to 8/3 and snap the aperture forward to 0-2. This will provide the same trajectory as above but with a larger, easier to see through rear sight. Use this setting if you also have the M68 mounted as it’s quicker to transition to if the sight fails.
11. If you have an M68 CCO (Aimpoint CompM-XD) optical sight, battlesight it to 50/200 as well. You can shoot to 300 meters by merely holding “over a dot.”
12. This battlesight zero is valid to 300 meters for both the M16A2 and M4 Carbines and their AR15 sisters. It’s valid with any ammunition that approaches the specs for M193 (55gr) or M855 (62gr) Ball ammunition. It works for both rifles and carbines due to the offsetting influence of higher muzzle velocity in the rifle being offset by the longer sight radius that moves bullet strike less per click. This is battlesight, not X-ring shooting!
13. This battlesight zero does not reflect the doctrine of the US Armed Forces, however, it reflects the personal use of these weapons in combat and in training for over 34 years.
14. Comments to: Lt. Colonel Chuck Santose
Original document: 990104
Copyright 1999, 2000. All rights reserved.
Analysis: Lt. Col. Santose’s improved zeroing procedure is mathematically correct and ideal for all situations. It allows the shooter to use the small unmarked aperture at all distances, as well as the 0-2 aperture for anything out to 200 meters. His recommended adjustment of the rear sight elevation was simple and took less than a minute (there’s a reason he tells you to leave the Allen wrench in there so make sure you follow directions).
