I'm not sure if anybody is still wondering about the assault rifle discussed on page 1 of this thread, but I thought I might shed some light on the subject.
(Keep in mind that we can only see certain parts of the rifle, so it's impossible to say everything about it. The receiver, hand guard, telescopic sight and front sight are the only parts I can make out.)
The rifle pictured appears to be a poorly copped Colt M4A1 equipped with parts from the SOPMOD suite.
-The receiver looks like a standard modern AR-15 receiver, though it isn't possible to tell what caliber it's chambered for from this picture. I'd say 5.56 x 45 NATO, but who knows. The receiver is missing a bolt catch, which I believe was a mistake on the person who designed that particular model. The upper receiver has a M1913 Picatinny rail, a feature designed by Knights Armament Co. and Colt around the early 1990's.
-The hand guard appears to be a Knights Armament Co. Rail Interface System (RIS), also early 1990's.
-The telescopic sight looks like a Trijicon Advanced Combat Optical Gunsight (ACOG) TA01 NSN. This is also a poorly made model, lacking certain details that would help me identify it's method of mounting or weather or not that's a reflex sight sitting on top.
-The front sight looks like a standard AR-15 fixed front sight.
-The rifle's muzzle is not visible, leading me to believe this is a short barreled rifle we're looking at, with a barrel length of either 10.5" or 11.5"
All of these parts were featured on the original M4A1 SOPMOD, a weapon system which started it's life around the mid 1990's and saw service with special operations forces around the world.
On the subject of Raul's slung rifle, we can only make out the stock, which appears to be a
Magpul PRS- a sight which can be affixed to many modern rifles and even shotguns, so I don't think you can accurately speculate on whatever it may be. I will say though, that stock was not designed for carbine length rifles like the one mentioned above.