I agree with Athenian, no real Bretonian pilot would mount anything but Splitters and Sunrails, if only for national pride. (All the houses, as it stands, are very nationalist)
On top of that, the ceasefire (which is more of a "Stay out of each other's ZOI") that currently exist between Bretonia and the OC is a secret, a lot of people suspect it, but largely lack the evidence. Similar to how Bretonians accuse Kusari of cooperating with Corsairs, as baseless as it may be. (I'm actually not very knowledgeable about the Kusari/Corsair dynamic, someone should post a link.)
Mounting Krackens would lead to obvious evidence for all to see.
As for the QCP angle:
How close are the OC and QCP? I'd think they'd be in competition over pirating territory.
But assuming they put aside their differences to fry the bigger fish, there's still not a lot of reason for gifting guns to the QCP. Outcast tech is highly advanced, and when you give to a band of marauding ultranationalists, who knows where it will end up. It's not like they'll just hand it back after the war.
Even with the less-than-hostile status between Bretonia and the OC nation, neither side wants to give valuable technology to each other, they certainly aren't allied, and certainly aren't friends.