The ejection of cases of any of the cheaper Russian 55gr .223 I have used goes to approximately my 4 o'clock position and flings a good distance.
The other week I shot some M855, and whilst every single one ejected with no problem, the cases all went forwards onto the bench by maybe a foot to my 2 o'clock position. I shot another couple of mags of 55 grain .223 after that and they all ejected to the 4 o'clock again.
The rifle has a Stag 2H upper with the semi-auto bcg it came coupled with an H buffer tube. I had originally thought that the M855 with it's heavier bullet would just cause the case to eject further and not actually alter the ejection pattern.
Is it just an instance of the round working differently with my particular combination of bcg and buffer? I didn't try rapid fire with it and now wonder if it'd cycle properly if the pace was upped.

Probably more like the difference in powder burn rate. Burn rate changes the impulse.

That sounds pretty normal to me... different ammo will eject in different directions. As long as it's working I wouldn't worry about it. :)
I'm not an expert... just a guy who shoots...

Just shot some .223 and 5.56 through a friends M-4 clone this evening. Wolf landed at around 3 o'clock in a nice little pile and the RORG 5.56 landed in the 1 o'clock area in a nice little pile.

1DD

Normal. My 3 AR's do the same thing. All .223 shoots about 4, all 5.56 shoots about 2.

Okay,cool. Thanks all for your input.