Although the GP100 is one of the easiest guns to disassemble, having the Ruger Popper from Brownells makes it a lot easier to take the gun apart. It's well worth the money.
Of course having the proper tools for any job makes it easier.
I also highly recommend that when any assembly is taken apart, such as the trigger assembly, do this inside a clear plastic bag. As the website stated, springs will fly!
The clear plastic lets you see what you are doing too.