Introduction:
Chasing down an opponent when they're recovering grounded is extremely dangerous, especially when they're recovering FDFT. If you can use an option that covers a wide variety of options, rather than relying on yomi to catch your opponent, the safety of it increases exponentially. In the case of CH d/b+3, the opponent is left FDFT with Dragunov slightly to their side, so the risk is there, but there's a slight advantage to being to their side.
Discovery:
Credited to tyler2k
Testing/Development:
So I'll just come out and say it, on the surface f+2,4 seems to be the perfect oki catch. It catches everything. Out of all the practice settings I've tested, I've only seen it miss a couple times on a specific side roll. As I was about to write this, I couldn't remember exactly which roll it was so I went to test it again, but I couldn't replicate the case. I've tested both sides, both rolls each five times and it hasn't missed since.
What makes f+2,4 really exciting is that if you're fast enough, f+2,4 will catch the opponent BT on quickstand. This will fully wall splat the opponent for B! combo and can setup BT forced KND options, such as empty jump WS+2 tech trap. I'm not sure of the speed required, but on my PSP I can land it about 20% of the time. With a little practice I'm sure I can bring that down to at least a 33% success rate.
So exactly what makes f+2,4 so good? I'm in the process of figuring it out, but in this case it looks like f+2 will catch quick stand and the 4 has enough tracking to catch movement to either side, as well as (f+2),4 being a safe, CH launcher that also wall splats. Unfortunately the CH launch will not fully land nine out of ten times, due to the angle, but the wall splat will occur on all wake up options, not just CH.
Edit: After a good amount of thought and reflection, I don't believe the BT catch is guaranteed, as it is high. I'll need to do more testing when I'm more awake.
Video Examples:
TBA
Conclusion:
For now f+2,4 looks like Dragunov's best option after CH d/b+3. It covers such a wide range of options that it's almost to the point where your opponent does anything once the frame opens, other than staying grounded, they'll be hit. Until I fully test wakeup options for the opponent on whiff, from the opponent staying on the ground, I can temporarily deem f+2,4 the follow up of choice.