Iran is a sovereign (SP?) nation that either has nuclear weapons (doubtfull IMHO) or will soon have nuclear weapons (almost certainly IMHO ). They have tanks, subs, F-14s with Phoenix missles (almost certainly not working due to lack of parts) anti aircraft missles, etc..... and your're worried about getting a .50 rifle.
Uhmm ... How much time have you been spending over the anti's sites reading the Bovine Scat about the .50s ?
The IEDs ( stacking 3 anti tank mines or using an SA3 war head is definetly improvisation )have taken out (destroyed tank killed some if not all of crew ) a Abrahms. They already have the russian heavy machine 12.7 (?) in large numbers. IIRC the US army has counter sniper teams already at work and can deploy ( or do, I do not know for sure ) electronic system to located snipers.
Actually since the rifes are serial numbered I'd be willing to guess that the politicians would love for them to be used against us in IRAQ because at least one would be captured then it would prove that the IRANIAN goverment was arming the insurgents against us in Iraq, not just individuals fighting for "religous beliefs".
NukemJim