I'll be getting to the SR-7 shortly. Remember, this thing is very quick. That makes it very suitable for close range sniping. So by close I don't mean SMG range, I mean 60-20m at which point the default scope and silencer is a really good idea. That's how I intend to use it at least. Unless you're desperate for an auraxium medal on it and already have one on the rams .50 this isn't the ideal rifle for longer ranges. Not that the SR-7 wouldn't work for that, it's just that the rams is empirically better with higher damage and higher bullet velocity.
So yeah, in short, default scope, silencer, get in closer. I've done some of that in the past and it's actually really fun and can potentially work extremely well. I normally don't go with the x12 scope unless I know I'll be 250m+ away. The reason for that is that I struggle with the x12 if I get close and I almost always end up closer than anticipated as I like to run in squads. If you're an infiltrator in a squad and you're more than 100m away I feel as if I'm not actively contributing unless I manage to find that peeerfect spot, which I rarely do
My standard scope tend to be the x10 or x8 depending on my mood for the day, normally the x10.