How does air pressure affect water guns?
If you mean how atmospheric pressure affects water guns, then that depends. If the atmospheric pressure is higher than normal, then the performance of a water gun will be lower due to a decreased pressure differential (for the same amount of input work). If the atmospheric pressure is lower than normal, then the performance of the water gun will be higher than normal due to the increased pressure differential. Because all water guns (whether they are the finger trigger, hand pump, air compressor, etc. type) have some sort of input work this applies in general. If you mean the working pressure in air pressure powered water guns, the pressure affects performance very much. However, there are diminishing returns on higher pressures. I have done testing with a water gun and I can get about 90% of the range of a 100 PSI shot at 60 PSI. That isn’t a general rule and only applies in that particular water gun, but as a general rule pressure increases will result in diminishing returns in range
