At work some of the people take these 36" air wands / blow guns and have
made darts with foam earplugs and a sharpened wire, they shoot and kill
pigeons with the darts. Some others have fire set screws through the air
wands and claim they shoot pretty hard. From that kind of idea I could
construct an air gun and use darts or "bullets", may not kill a raccoon, but
I would think it wouldn't be coming around after getting stuck with a couple
of darts or hit with set screws.

Would ~100psi from a compressor shoot a projectile hard enough to deter a
varmint?

RogerN