The attack on the temporary residential outpost of the American Ambassador, seems to be modeled on The Benghazi Incident of 2012, where the compound of the American Ambassador was overrunned by insurgents in Benghazi, Libya, the result of which was the Ambassador died as as a consequence of the skirmish. Edit: along with 3 other Americans. Two of which were former SEALs.
When Ray is showing Lopez the weapons he uses, he says he recently has been using the .416 for a sniper rifle. He is referring to the .416 Barrett, a proprietary cartridge developed in 2005 at the request of the Naval Surface Warfare Center, who asked them to develop a smaller and lighter alternative to the .50 BMG. The .50 BMG is usually used as an anti-material rifle, but Navy SEAL teams wanted a cartridge with the range of a .50 BMG specifically for use as an anti-personnel round, as even at extreme long range the .50 BMG could go straight through a human target and keep going. Barrett, the company that makes the M99 and M82 sniper rifles that fire the .50 BMG, took the .50 BMG case and shortened it a bit and necked it down to fit a .41 caliber bullet, as such the .416 Barret can be fired out of the M99 and M82 rifles simply by swapping the barrel. The .416 fires a 398 grain, solid brass bullet with a muzzle velocity of 3,150 ft/s and 8,767.4 ft-lbs of muzzle energy. The .416 Barrett retains more velocity and energy at 1,000 yards than the .50 BMG and maintains supersonic velocity at up to 1,900 yards (1.2 miles), as such it is now the preferred sniper rifle of choice for a human target at distances of 1,000 yards or more.
On March 31, 2004 Iraqi insurgents attacked a convoy containing four American contractors from the private military company Blackwater USA ( later renamed Xe Services followed by Academi) who were conducting a delivery for food caterers ESS. The four armed contractors, were killed and dragged from their vehicles. Their bodies were beaten and burned, with their charred corpses then dragged through the city streets before being hung over a bridge crossing the Euphrates River. The incident was known as The 2004 Fallujah ambush .
Ray mentions that sometimes Clay uses the 14.5 when he is on sniper duty. He is referring to the 14.5x114mm, a Soviet heavy machine gun and anti-material cartridge. The DEVGRU uses this cartridge when they need an anti-material rifle while doing a black ops mission in areas where this cartridge is used frequently, as using their standard .50 BMG or 20x102mm rounds would give them away as American.
Imam - a leader in the Islamic community, they are usually the leaders of worship in a mosque. For Shia Muslims an Imam is not just a religious leader but also a leader in the community, the title is only given to those who are considered to be direct descendants of the Prophet Muhammad. In some Islamic countries like Yemen Imams have both religious and secular authority, the Imam is the leader of their tribe in both religious matters and in matters of dealing with other tribes and groups.