Determining the force required to compress an internal retaining ring.?

At work we install retaining rings into a housing to limit the movement of the roller bearing and to hold the shaft in place. After complaining about my hand's soreness from having to repeat the task 300+ times a day, and not much being done about it on the engineering level. I've decided to come up with a case on the safety aspect of this repetitive motion.

RotorClip goes on and on about spacial dimensions but says nothing about actual compression force. Does anybody know of a good method in determining the force required to compress a ring of specified material and size?

I wont need help with the leverage of the pliers diminishing the force required for the ring itself. Thanks!