hmm..ok, a lot of this is probably moot if it's a game, but a sniper rifle is a pretty specific firearm. Here's a few things that will make it more towards that (on the other hand, this would make a great assault rifle..;)
Sniper rifles have a low rate of fire, and need to be pointed very accurately. Quick fix would be to extend the stock to the usual length, to improve the aiming grip. The clip's a bit long, and would interfere with the balance and positioning of the gun (often on a sandbag, bipod, etc), but a smaller clip would work fine. The pistol grip is good for holding at a 90 degree angle, but I'm not sure if it's what you're looking for in a sniper rifle. A lot of sniping is done in the prone position, which the grip would throw off a bit.
You got the chops to do a good rifle here, and this one works perfectly well as a short-range, high rate of fire weapon. I'd keep it, and then 'gussy' up another one for those long-range duties. Keep at it, it's lookin' good.

What kind of game exactly?

To pakled. That stock you see is extendable and you're rite it is actualy a cross assult and sniper rifle. It uses rail gun technology and belongs to a cyborg. To spaceboy. It's a stealth game very much like Metal Gear Solid if you want something to compare it to. Thanks for your comments they're well appreaciated(I hope I spelt that rite).

give it some depth, looks flat

I dont want to offend you, but I find it rather ugly. It wouldnt be very useful, neither as a sniper, nor an assault rifle. For an assault rifle its far to clumsy and for a sniper rifle the long magazine makes it impossible to fire it from most prone positions. Perhaps it will look better if its textured.

Your comments don't offend me they're very helpfull. I want people to tell me wether it's realistic or not as it will be used in a game when it's finished.

The clips: add more detail to them.