Well, a better (more convoluted) way to do the "tissue test" would be to get a 6 mm (outer diameter) clear hose. Stick it in the hop unit and put some colored water in the tube. Fire full auto, and if there is any air escaping there, it will move the water in the tube. Even the tiniest bit of air will move the water line in the hose. I'll share my tappet spring, and be sure you have something similar. I don't know how many "pounds" my tappet spring is, but it is a lot. I have bought a couple "upgrade" spring sets before, I still removed coils from the tappet spring. Not sure the actual ratings but they were "better" than some factory tappet springs. Most normal builds they would be fine, but getting close to 50RPS I rather be sure. Maybe that is one bad *** spring, I don't know. It might be fine.