Only guaranteed string after 4SKRC are f2 or f3 (maybe b3 too, but is has whiffing issues)
Also, hits EX Forceballs are both mid but even the straight one whiffs against crouch blocking. It is a pointless projectile and should get fixed too.
I love 4SKRC into 333 or 113 or 114 but the first hit whiffs anyway against crouch block, and not only against Cassie. I want to emphasize this point: it whiffs against almost anyone, Cassie is just an example.
If you need great chip damage to end a round after a connected nutpunch, and don't feel like pushing your luck because of random whiffs, I suggest trying 333xxhalf charged nutpunch...it does nearly 7% on his own and is a true blockstring.
We know a patch is coming, let's hope for the best.