I have used the 50/200 zero method recently when instructing a police patrol rifle class and it works great for our applications.  Some one should promote the Colonel to General.
My question is this: I am going to mount a M4 barrel on a Colt A2 upper with standard A2 sights (8/3 markings).  Since the new barrel will have a shorter sight radius what will the procedure be for employing the 50/200 zero with this setup?
Or should I make life simpler for everyone and switch this sight with a A2 (6/3) sight off a bushy detachable carry handle that I'm not using?
Second question:  My reserve unit is a small Detachment of MPs.  We might well be activated in the near future. We are equipped with standard A2 rifles.  I would like to zero everyone on the 50\200 zero but we will be limited to a 25 meter zero range. At that range what should the point of impact be to get the desired zero?

1.2" low

Duke --

My computer with the ballistic data will be down a few more days (the old software won't run on a fast PC due to Pascal timing loops and no source code).

IBSZ came out of an attempt to create an easy way to zero the M4 Carbine for RC units without access to military posts at home station.  Thousands of civilian ranges have surveyed 50 yard ranges.  Lots of coincidences turned up and IBSZ works for both rifles and carbines and with both M193 and M855 Ball.

Colt's M4 barrel will probably have problems in a M16A2 receiver based on the M4's front sight.  I could not zero this barrel and keep the front sight post lower than the ears.  The sight on the detachable handle has a thinner base, so the sight will sit lower on the rifle.  You may have to use the sight off your detachable handle.  Bushmaster M4 barrel had no problems in the M16A2 upper.

Try zeroing with the standard sight before going to the trouble of swapping them.

-- Chuck

Chuck, what the heck would you know about the IBSZ? Hahaha! [:P]

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-- Chuck