In the case of the Kraken Bow from what I see they're not missing; the shots are being dodged. This may sound like a distinction without a difference...
I'll take a look at the targeting mechanics for the Kraken Bow and Gun and see if there is anything that I can improve in the short-term. No promises...
Certainly would be interesting if done correctly - however, it's going to be extremely hard to balance such a similar proc between these two Arcanes....