I doubt that dimension of PL10 and PL15 are same..
If the online information is correct then, it has a length of 4 meters (20 cm more than AIM 120D) and diameter of 20 cm (2.3cm more than AIM120D). The volume packed inside PL15 wont be that high when compared to 120D.
So unless china has developed a new kind of fuel which has a very high calorific value and longer duration of motor burnout, about 25 to 30% increase in range is not possible in sustained kinematic performed.
I though this might be a air breather, but online pictures may not suggest same. Also the biggest give away for not being an air breather is that it has dual pulse motor.. So, for me this is a 150km kind of missile, but its still a real threat to adversaries..
The length is only slightly more than the SD-10 (it's PL-12 not PL-10), and the diameter is identical. Remember, this thing is meant to fit into the internal bays of J-20 and FC-31. The US is doing something similar with the JATM, big increase in range. And while some are speculating that it will be a much larger 'outsized' missile, I think that's highly improbable. AMRAAM delivery to the USAF cut-off is 2026, after that it will be JATM deliveries for all platforms including the F-35.
On the range and propulsion, I don't read too much into the range quotes. They are meaningless without an equivalence of launch parameters and flight path. Take an AAM's quoted range at x km. What's the altitude that it's launched at? If the missile is a Meteor like ramjet it's optimal launch altitude will be completely different and much lower than say an AMRAAM which is best launched at high altitude. Initial velocity for both can be maximised, but what was it to reach the quoted x km range, M1.4? Then was that max range achieved by lofting like is done with AMRAAM like rockets? What's the AAM's AoA while it climbs? It may sound arbitrary but it absolutely is not. And what happens at that max range, is the object completely out of energy, or does it no longer have enough energy to close the deal vs an evading aircraft?
And even factoring for all of this you have to consider different flight paths. An AMRAAM will happily loft well into high altitudes and maintain energy better in thin air, and it will burn like a rocket until it runs out of fuel and then cruise until it runs out of energy. Whereas the Meteor will prefer thicker air, the ramjet will lose efficiency at higher altitudes. Instead Meteor's throttleable, so that gives it other options. And nowhere does anybody claim that PL-15 is an airbreather, it's clearly a rocket motor with no visible intake. I've seen some theoretical flight models for AMRAAMs, they continue lofting well after reaching max velocity, from then on it's no thrust and all drag. PL-15 would do the same but keep some fuel left over for a final push.
What should concern you isn't whether x km arbitrary max range makes sense. Instead just observe the response of the USAF, the push for the JATM, and how the Chinese are viewing this missile.