Ryan,
there`s a book called "The Airgun From Trigger to Target" by the Cardews, father and son i think. It shows how PCP and spring guns work and the principles involved. My girlfriend bought me it for xmas and though i don`t read many books
, because i had an interest, this book was very informative and i`ve read it a few times now. Basically, your pcp is fantastic engineering but your spring gun has even more weird, complex things happening inside like combustion! I think it costs about £17 ish but for the airgunner interested in how it all works a good investment.