So, the quick question is: Does the explosive bomb feature of the bomb from a Gun Chemist cause the 15 foot cone to be a 15 foot cone, or a 15 foot cone with another 5 feet around it with the splash of 10 feet?
The long form explanation:
Explosive Bomb: The alchemist’s bombs now have a splash radius of 10 feet rather than 5 feet.
Exploding Bullet*:gun chemist’s alchemical ordnance splashes adjacent targets as though it were a splash weapon.
Alchemical Ordnance (Su): If the gun chemist uses alchemical ordnance to make a scattering shot with a weapon with the scatter quality, each creature in the area instead takes additional fire damage equal to ... etc...
So you can shoot them with a bullet for a 10' radius splash (25 squares) or scatter shot and do what?> 6 or 7 squares (depending on a corner or side cone)? Or can you pick up the edges with 10 foot of splash and splash out (20 squares)?
Explosive bomb scatter (no target set on fire)
Explosive bomb splash (target is on fire if hit directly, no save)
I'm thinking, just as a GM call, I'm going with the Explosive Bomb Scatter. Thoughts?
Alchemical ordnance is treated like an alchemist’s bomb for the purpose of discoveries, though such discoveries ignore any effects associated with a bomb’s splash damage or radius unless the gun chemist also applies the exploding bullet discovery.
Discoveries: A gun chemist selects alchemist discoveries as normal. He can also select from the discoveries below, which are unique to the gun chemist. Discoveries marked with an asterisk (*) do not stack, including with other alchemist discoveries marked by an asterisk that modify bombs. Only one such discovery can be applied to an individual alchemical ordnance.
also even if somehow you could add both discoveries the gun chemist ability (which for some reason you cut up short) say:
"..If the gun chemist uses alchemical ordnance to make a scattering shot with a weapon with the scatter quality, each creature in the area instead takes additional fire damage equal to the alchemical ordnance’s minimum damage.."
this changes how it work and it no longer has splash damage added to it so abilities that alter the splash have no effect in this case.
in fact the entire damage is set to work as if it's only the splash (but doesn't name it as such so effects that work on splash won't work here).