AR busts shields with 12 bullets?

In the Multiplayer ViDoc released yesterday, there was a small 3 second vid showing, in first person, a player firing the AR on another player, and I counted how many bullets were fired to break the shields. Assuming he didn’t miss, the AR broke the spartan’s shields in 12 bullets, and I would assume 4 more bullets would be needed to take out the remaining slivers of health. Unfortunately the clip ended before the spartan died, but it did show the shields burst. Also, the enemy player in the scene was at midrange, which means the AR player could have missed shots. This could mean that the AR breaks shields in 10 bullets for all we know. What do guys think?

I think it would be good if the AR killed in 13 or 14 shots, meaning that it could have missed some in that footage. If I remember correctly, it took 15 to kill in Halo 3 and 18 in Reach.