Editing Choosing the Right Plastic (section)

=== Heat Resistance ===
Each plastic has what's called a "glass transition temperature" (Tg) which is the temperature at which it starts to lose its crystalline structure and begins to flow and warp. If, say, your receiver hits Tg while firing, your gun may start to meltdown and malfunction. Some plastics have glass transition temperatures low enough that they cannot withstand the open sun in certain regions' summers.

In general: the higher the printing temperature, the higher the continuous round count.