Originally Posted by uv_halo
The top photo I'm assuming is from an SA-8?
Yep. I assume it is a relief valve, but a non-adjustable one set rather high.
Won't prevent a velocity spike if you manage to get liquid CO2 past the regulator, but should be enough to prevent damage to the gun if some officer left it gassed up in the trunk of his squad car in the middle of July in Arizona.