Introduction:
Getting your opponent on the ground is definitely one of the harder things to do with Dragunov, luckily once they're on the ground they're in a world of hurt. Even though the options may slightly vary dependent on how they are recovering from grounded, the end resultant will often be the same: "small" combo, regrounded/KND, and almost knocked out.
FDFT: (f+1+4 and f,f,+1+2)
If given the choice between being left FDFT or FDFA, a smart player will take FDFT every time. There's two main reasons, 1) If the opponent makes a critical mistake, FDFT d+3 launches for a full combo for almost every character. 2) Wakeup 3 and 4 (from FDFT) are only -12 on block, while wakeup 3 and 4 (from FDFA) are -14 or worse on block making them launch punishable by a good portion of the cast.
So when a smart opponent sees that they are left FDFT, they tend not to panic. Unfortunately for them Dragunov's strong wakeup option comes from FDFT, namely b+2 for safety and b+2,1,3 for max damage. A simple b+2 check will catch quickstand, recovers in time to guard against wakeup 3/4 (assuming you guess correctly, but note guessing low is by far more in your favor!), and if they do nothing can be followed by a FC d/f+3 or f,f+4. If the b+2 catches, WS+1,3 and WS+1+2 are guaranteed for an additional 47+ damage.
If you're feeling a little more frisky, you can follow up with b+2,1 (hit confirm 3) or outright b+2,1,3. The chain (for instance) f,f+1+2, (quickstand) b+2,1,3, WS+4, d+4,4 which does a whopping like 154 damage. Please note that the opponent can attack during the b+2,1,3 string, but in any case cannot escape the final 3. Instead of KND, the opponent will get hit by the 3 as CH and be attack thrown where they will be left FDFT for even more 50/50s. The major downside to b+2,1 and b+2,1,3 is that both strings are launch punishable on whiff, the opponent has time FDFT d+3 between the 1 and 3 for a full launch. The only time that one should even consider using this option (from standing) is for pure shock and awe or a large health deficit to make up. Instead, the best time to use b+2,1,3 is if you scout a roll away while they're recovering from grounded, follow them and time b+2,1,3 to catch them as they're standing up as this is the safest way to use it.
One final option worth mentioning for f,f+1+2 is that if the opponent flinches while grounded, using a d/b+4 will catch them with relatively no risk. Unfortunately d/b+4 is a generic low, therefore is negative frames on hit, so be sure not to go crazy with follow up options.
FUFA: (f+2+3)
Similarly to Dragunov's FDFT throws, a b+2 will catch quick stand options, but in these cases the opponent is more likely to roll away as the distance is farther. As such there are two solid options to catch the opponent, 3,1 strings (both standing and dash in) and iWR+2. Using 3,1 and 3,1,2 is a strong option because it leaves the opponent open to wallsplats and non-strict follow ups. Dependent on a few variables, it's possible to follow up 3,1 with a 1,3,2, B! and do a forced KND option such as d/f+3 leaving the opponent once again as FUFA. It's also possible to use 3,1 and follow up with d+4,4 or d+4,1,3 dependent on how you believe the opponent will react due to level positioning. Finally 3,1,2 will work in all cases leaving the opponent FUFA but they're able to tech to recover.
The other notable option is using iWR+2 to catch the opponent for a guaranteed bind and follow up. While the damage potential is lower, the consistency is there to set up forced KND 50/50s and wall carry. Though as I mentioned in the last paragraph, the wallsplat options are drastically reduced as iWR+2 causes a low bind as well as the opponent being hit FUFA.
Guaranteed KND follow up(s):
1) The first notable follow up is post u/f+3+4, d+3 is guaranteed and will catch the opponent BT on certain wake up options. If you're anticipating quick stand for instance, you can follow up with d+3,4 which will both hit, the other nice side effect is that if the opponent does a wake up kick it's possible for the 4 to hit CH and cause an ass stun that must be teched. Please note that d+3,4 is -frames on hit and attacks out of BT are decently fast, so don't try attacking.
2) BT d+3 isn't a particularly useful move but is good for tossing in every once in a while for keeping the opponent on their toes. I've mentioned a couple options, earlier, that are guaranteed (such as qcf+3) but the most notable is definitely d+2. If the opponent stays grounded, the d+2 will hit them and slightly push them away, but if the opponent flinches, WS+4, d+4,1,3 is guaranteed and fairly easy to hit confirm.
3) Off-axis juggles are bad and BT juggles are even worse, but it's possible to sneak in a little more juice off your BT juggles. Simply do your standard/BnB BT combo and do a dash in d/f+3. Like standard d/f+3 spike, there are wake up options to catch your opponent for a small combo, but unlike them a d+3 is guaranteed in this case. As with point #1, if you anticipate quick stand, d+3,4 will fully catch the opponent BT.