Okay First It's SNIPER not "SNIPPER" the closest Military Jarrgon too SNAPPER that I know Is SAPPER a combat engineer.
Second in the Case of the M16 With a thicker barrel this is too add rigidity and change the harmonics of the barrel too allow better accuracy, it is not however a true sniper rifle but rather a Attempt at a Designated marksman's Rifle.
Third the Rifle looks more like a Accuracy international Rifle then a Default M24. the Questions that come up are first Caliber what does she shoot? second what power is her optic and third her rifling what kind of twist is that barrel?