Had another person ask me about the Z setting on the AR15 carry handle. This setting, along with the great deal of misinformation about it, tends to be confusing.
If you are using a reduced range 25 meter zero on a M16A2/M16A4 or other 20 inch barreled rifle, you use the Z setting when you zero your rifle.
If you are zeroing a M4/M4A1 or other 14.5/16 inch barreled carbine you DO NOT use the Z setting.
What about Matech sights? It is exactly the same, check out this link 670-20 if you don’t believe me.