The gun was a Scaramanga Special, as shown by the earlier scene where it was being assembled. It was probably only a single-shot gun.
Fridge Logic: At the end of Ghost Protocol, why didn't the new iPhones that Ethan handed to his team self-destruct? I thought all mission briefings did that...
They hadn't listen to the mission statements by the time the credit rolled.
In Ghost Protocol, why didn't Hendricks toss the suitcase off the ledge and keep fighting Hunt to buy time?
I assume he was protecting it with his body, so it wouldn't be too damaged to work.
Fridge Horror: In the first movie, Secretary Kittridge sent Hunt's IMF team to retrieve a stolen list of Code Namesas part of an internal "mole hunt" - and was completely unsurprised when Hunt was the Sole Survivor, whom he thus believed to be the mole. He effectively sacrificed the entire team to catch a single mole. The whole "disavow any knowledge" meant the loyal team members were expecting to stake their lives on their talents without a net, but sending them on a Suicide Mission without their knowledge? Granted, he was really pissed off afterwards at the deaths and there was really no other way to expose the mole, but dude, that's cold. Justified, but cold.
Perhaps he wasn't expecting the mole to reveal him/herself by killing the rest of the team, but when he got the news that they all were dead, figured out quickly that this would expose the mole anyway.
Additional thought on this: Kittridge did have thew other team to watch it was going on, his plan was likely that the mole would reveal him/herself by some actions that the other team would spot, but expected this to be done in a more sneaky way. However, Kittridge throughout the movie is shown to not react all that strongly to anything that happens, even things like seeing Jim alive, so it is likely that he wouldn't react to strongly to the team's deaths either, and that he would quickly figure out that Ethan was apparently a likely mole.