I have seen several of the Kinyons in action and used the first Kinyon once at a demo. They are fine hammers but my air compressor isn't big enough to run one. If you have less then a five horse power they can be a little starved for air so a fellow named Zoller developed a small air hammer. Here is his link
Zoeller Forge It can use a small home style air compressor. Good luck with your build.