Introduction:
Generic low poking can be a real pain in the ass, especially since Dragunov is lacking a damaging low crush launcher. One can argue that u/f+4 can get the job done, but if they opt to WS attack or spam jabs instead of continuing to generic low spam, it's very possible to be bobbled mid-air for small combo; as such it's not best idea to use u/f+4 to counter on anticipation.
System Info:
The good news is that generic moves usually have very poor properties on block and hit, for instance generic low FC d_d/f+3 is launch punishable on block and even though the animation may slightly change, it does not change the punishment properties on block. Now this article primarily deals with "generic low spam" which in essence means kicks, this is due to generic punches out of FC (e.g. generic d+1 and d+2) being classified as SMid. While this makes defending against generic "low" punches easier to defend against, they are usually +frames on hit, thus must be defending against accordingly on hit.
With that being said, the first thing to realize about generic lows are that they do not give frame advantage on hit. This is most likely due to generic low kicks being classified as low while generic low punches are classified as SMid, so it's a minor trade off of properties for frames.
Countering generic low spam:
There's two main options that the opponent can perform after landing a generic low, either to do an additional generic/non-generic low or to do a WS/jumping attack out of FC. Since Dragunov has a i12 mid, he can effectively take care of both options with little thought. It's pretty simple, if you get hit by a generic low, immediately throw out d/f+4. A generic low is about ~ -3 on hit and realistically the fastest option the opponent has out of WS is i11, therefore d/f+4 will beat them by 2 frames granting CH damage.
Now to be fair, using d/f+4 doesn't sound very fun nor does it really discourage the use of spamming generic lows in the future, so what else can be done? Well since they're left at negative frames, it's possible to treat a generic low hit as a blocked d+1. Namely a 1,2 CH hit confirm will nullify any WS launch or generic WS 4 option and will knock them down giving future oki options. Unlike d/f+4 though, 1,2 confirming will not counter an additional generic low and you'll be in the same predicament you were just in one second ago. So in this case using 1,2 is a wild card that will grant you more damage if the opponent guesses wrong.
Either way, both options are safe when performed properly, whether the opponent attacks or not.
Covering my ass:
I'm sure there's someone out there who's saying, "What about low parry?" Yes, low parry is a valid option as it will stop both a generic FC punch as well as a generic low kick, but will that low parry save you from a random FC u/f+4 or WS 2 launch? Not exactly. Secondly, there are a few characters with FC options that will high crush weakening 1,2 hit confirming as a counter option, though luckily they are usually very punishable on block if your opponent decides to use them instead. Moral of the story is to just be aware of your opponents options before trying to hard counter them.