As mentioned in my previous game report, a 5.5kg Elite Upgrade Spring was not enough to push the Thermal Hunter to an acceptable muzzle velocity range (that spring has since been moved to my Tri-Strike). For a stronger main spring, I looked to NerfTurf, an Australian based spring seller. I ordered their 10kg Thermal Hunter spring.





In preparation for this spring upgrade, I reinforced the priming bar with epoxy putty.



The NerfTurf 10kg spring is very long, and has a golden finish. When installing it in my Thermal Hunter, there was a lot of precompression and all reassembly had to be done with one hand holding down the plunger tube. This was rather inconvenient as reassembly of my Thermal Hunter already needs two hands. Nevertheless, I managed to get the blaster closed up.



Once installed, I was getting an average of around 105fps with used grey Koosh, even with the AR still intact. I was very impressed with its power, and the blaster had quite a kick to it. The raw data can be found in the Thermal Hunter tab in my chrony sheet.



I am not a very strong person, so priming the Thermal Hunter with this spring was not easy. A factor to this is the Thermal Hunter's fairly flat pump grip, which I find less comfortable and less easy to grip than a bulkier grip such as Gavinfuzzy's Retal pump grip. As a result, firing multiple shots from the Thermal Hunter was surprisingly difficult, and I have to make a major deliberate effort to prime, which is not usually the case for most of my pump action blasters. While I do intend to give it a shot at the next game I go to (likely next HvZ), I am concerned that I will be unable to use it for a whole game due to its prime strength. Nevertheless, if you can handle the prime strength and are looking for a decently powerful Thermal Hunter upgrade spring, this NerfTurf one is certainly quite good.