You can seriously hurt someone with a Pneumatic Nailer and I would not hesitate to defend my home with one if it came down to it. If you think about it though, it is just air, compressed air. Amazing that air, coupled with a nail and a pump, can be such a powerful force. This all comes about with the use of an air compressor.
Air compressors come in many shapes, sizes and abilities. The most important factor in choosing an air compressor is to determine the maximum CFM (cubic foot/minute) the tools that you are using require. CFM requirements are tool specific, for example, a paint sprayer or framing nailer will require a much higher CFM than a brad gun or a trim nailer. An air compressor with a larger tank will typically have a higher CFM because basically there is more air available for the tool to use. More specifically, the CFM output is related to the pump size.
It is recommended that you purchase an air compressor with a CFM capacity of 25% greater than what you will need. The durability of the air compressor is directly related to how long the pump has to run to keep your pneumatic tool working. If you use an undersized air compressor for the type of tool that you have and the work that you are doing, you will reduce the life of the air compressor pump.