I'm with you, I'm guessing that it was one of those .50 caliber sniper rifles with a new tech anti-armor round... There was some concern recently that Iran had acquired (illegally) some high performance .50 cal sniper rifles. Alternatively Iran has made a 12.7 anti material weapon which, as some posts suggest may be being field tested see:
http://forums.military.com/groupee/forums/a/tpc/f/2741923366/m/1600037510001
Here's another interesting page with specs for the Steyr-Mannlicher sniper gun with a new 15.2mm Anti tank Sabot projectile which could have caused the so called "pencil hole" sized intrusion.
http://world.guns.ru/sniper/sn46-e.htm
I remember that there was an article last year about sales of these guns to Iran. Then lo-and behold, there was an article recently: Wednesday, 28 December 2005, 16:42 GMT US penalty for Iran sales 'wrong' Steyr-Mannlicher building in Austria China, India and Austria have condemned a US decision to impose sanctions on nine firms which it believes have supplied Iran with military equipment.
China, which is home to six of the firms concerned, has demanded that the US State Department lift the sanctions.
The Austrian interior ministry defended the sale of about 800 sniper rifles to Iran by an Austrian arms manufacturer as "unimpeachable".
Maybe in 2003 they were evaluating the effectiveness of the Steyr-Mannlicher... with the 15.3mm anti-tank round. And found it obviously effective.
I doubt it. Even the new U.S. SLAP (Saboted Light-Weight Armor Penetrator) round can't get anymore than 34mm of RHA.