[VanShuyten]

What do the carp sitting on the barrels of the six-guns mean?

[Broker]

Those are Dolphins. This sub got screen doors?

[moonshot925]

The silver and gold dolphins form the front sights of the revolvers. They represent the officer and enlisted submarine warfare community

[Lion Den Dan]

What do the carp sitting on the barrels of the six-guns mean?

They represent Senators Dorgan and Conrad, bottom feeders, who suck the life out of everything they contact.

[John S Mosby]

Those aren't carp, they are dolphins. Dolphins, real ones are fish with big scales (and incidentally delicious with an egg wash and baked filets).Submariners, whether officer or enlisted, must earn the twin dolphin insignia in the course of their training, which is on their patches and also worn in dress uniform.

Here is the symbol of the Submarine Service insignia (silver for enlisted,gold for officers)of the Silent Service: