The list of abuses that you can do to an AK just seems to never end. (Mattv2099 goes into detail in that regard) But, Taofledermaus shows how you can get an AK running without its main recoil spring. Turns out all you need is a few rubber bands connected from the front sight tower to the charging handle.

Surprisingly, the rifle looks to run well, but its hard to see the changes in recoil. That said, logic dictates that you can adjust the bands (number or strength) to tune recoil to your desire.