Question about laser bore sighting

[lupothebutcher]

I had an interesting experience today; my new laser bore sighter arrived in the mail so, naturally, I had to give it a try. The bore sighter is the cartridge type .233 rem.; I put it in my Sig M400 and dialed in the Eotech XP S2-0 to 50 meters, took it out back and scored very good. Next I put it in an Olympic Arms AR-15A3 variant and just going by the bore sight and iron sights, it looks to be right on; now, in both cases, the laser came through the barrels very clean with no distortion. Next I put in a Norinco QCA (or whatever they call their m4 variant) – this was my first AR and I’ve never been particularly impressed with it – I immediately noticed that instead of a nice clean dot, the laser was coming through the barrel distorted, elongated, and with spiral patterns from the rifling; it looked like a small solar system.
Has anyone come across this before? What can it mean? Chamber not lined up with the barrel? Bent barrel? Something else……?

 

[laurencen]

is the barrel straight? have you looked down the barrel

 

[Sniffer]

Bent barrel or the laser isn't seated properly (100% square)

 

[lupothebutcher]

I put it back in and pushed on the base which made it point out without distortion; this makes me think that the chamber is actually a little bigger than the .223 rem bore sighter, now I need to find out if .556 nato is, in fact a little larger than .223 nato which allows the bore sighter to sit a little funny in the chamber. I did drop the bolt on it and pushed the forward assist but this did not help.