Here are information sheets for 5.56 (the ammo itself, both M193 and 855):
https://www.northropgrumman.com/Capa...nFactSheet.pdf
Note M193, fired through a test fixture, is supposed to do about a minute-of-angle (by average mean radius) at 200 yards.
The spec for the M4 and 855 together as a
system (MIL-C-71186) is a 5-inch extreme spread at 100 yards (91.4 Meters).
If you want to dig deeper, goggle the mil specs ref'ed in the info sheets.
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