Hail, fellow imperial agents!
I made a sniper rifle models guide which shows the various models and their icons for (I think) all the rifles in the game.
The image is large, but that allows you to zoom in to see detail and choose properly. Also, because this game has so many rifles, I couldn't include all the color variations - just the model variations. Some may look like duplicates, but that's just because they have an added scope, etc. To find these search on your database site of choice (I use torhead), browse by weapon type "Blaster rifle" and then look through the icons to find an obtainable model.
So, happy snipin' - for you or a companion!
Hope it helps!
Sniper Rifle Model Guide