I don't recall it being in the second Matrix. Think back even farther.
Hint 2- It starred Danny Glover, and from what I saw of him in "Saw" and compared it to this movie, he still dosen't know how to handle a gun very well.
Your gun looks like some kind of AK varient, modified all to hell. If you look at the top rear of the reciever, it reminds me a lot of an AK. The side mount for the scope it characteristic as well. The front handguard and the stock are modified, as well as the gas system and barrel. Thats all I can tell you.