5.56-.223 POI shift

[rabiddawg]

Different powder, different projectile, different primer etc. etc.

556 and 223 are technically not the same. 556 is a higher pressure round iirc. Isn't the rule of thumb you can shoot 223 in a 556 chamber but 556 in a 223 isn't recommended?

I would have expected a point of impact shift but not 8-10".

Here is a good read
http://www.luckygunner.com/labs/5-56-vs-223/