This card is just aggressively bad. Let's start with the functionality, because that's where all the other choices on the card fail to accurate reflect.
Telescopic Sight requires a two-handed firearm. Now that seems okay at first, but then you remember that Marksmanship allows you to do this with any gun. And it provides an extra damage to boot. Now you may make the case that Marksmanship is only one use. But at best, Telescopic Sight is one use per turn. Yes, it exhausts for some reason.
You cannot make the snipe shot at Elite targets. Typically Elites are the scariest enemies, and the ones you're least likely to want to end your turn engaged with. So being able to plink away at them from range would be useful. Naturally, they have taken that away from the card. Please note that Marksmanship does not have this problem.
You cannot shoot an enemy in your face. That's really bad when using a two-handed weapon, as it means you now need a Bandolier so you can carry a second weapon or an alternative means of removing an enemy from your face to be able to continue using your weapon. Please note again, Marksmanship does not have this problem. This is the entire reason Springfield M1903 is bad.
You also cannot shoot into a connecting location if an enemy is in your face period, even if they are not the target of the attack. As someone with a gun, this is often going to be a thing that happens when trying to kill enemies. Marksmanship still doesn't have this problem.
Finally as a card it has the no Will sampler platter of icons which isn't exactly where a Guardian wants to be. Cards without doubled icons are a hard sell for me, unless you're always intending to play them for their primary function. This one doesn't have a good primary function, so it should at least make up for the 3 XP cost with good icons (which it doesn't).
So I keep bringing up Marksmanship which in itself isn't exactly regarded as a stellar card. It's cheaper for a single use than the scope, does more damage than the scope, and requires less XP than the scope. And did I mention you can put it on Stick to the Plan? Two scopes is 6 XP, but Marksmanship plus Stick to the Plan is only 7 XP for the ability to guarantee you'll see the card. Still doesn't require a two-handed weapon either, it's going to work on your .45 Automatic (2) if you're a mad lad.