There is absolutely no evidence (comfirmed that is) that it's any type of sniper rifle... The closest thing we can use to speculate it is that one Frankie update were he mentions a gun we've seen and not talked about, all he said is that it has a scope and some other cool stuff.. (beware, scope doesn't automatically equal a sniper rifle. The rocket laucher has a scope for example) But he didn't specificaly say it was that gun, so it can only be seen as speculation for the time being...