pmcaero wrote:aren't guns in essence longboards with a sharp nose and extra rocker?

No, guns are very specific, good volume (usually under the chest) for paddling speed to match and get that speed to cross the fall line.
They are narrow, often with more nose rocker and less in the tail they provide a long planing area to generate the speed and have quite different rail characteristics.
The nose is sharp and rockered, as a nose catch with any nasal volume spells instant wipe out.
Often there are channel bottoms to give even more speed.
They can be designed for specific big wave spots as a generic one shape fits all can fail.
You can ride a big wave spot on a standard longboard but it is most likely to fail in the drop. Make the drop and you will probably be well out on the shoulder and not really in the critical zone.
Sadly Name big wave spots also have a curse, they are on people's bucket list to be able say they have ridden them.
You see all the wannabees at pipe hooking into what little shoulder there is.
(Hey Ma I rode Pipe it ain't no big deal).
Same applies at other spots.
The long paddle out spots are not as frequented, as you need the knowledge to be able to get out and the wave stares you down and often exposes your lack of knowledge by smashing any number of time before you get out.

REJECT CYCLE!