The challenge with matching names to models is that there are many rifles with the same model, so you'd have to match all the name variations. Plus, each model has multiple color variations.
If there's a model you like, I recommend using torhead.com and filtering for "sniper rifle" "prototype and custom". You can then browse to find the icon your looking for, open those, and figure out which would be easiest for you to procure.
I know, not the easiest system...but hey, shiny guns