How can I know if the spring has been changed? (GP100)

[El Guero]

I just picked up a used GP100 yesterday. It came with two sets of grips: the stock grips and then Hogue pau ferro hardwood grips. I just looked and these grips aren't cheap, so I was wondering if there's any way to tell if there are any other mods, such as a changed spring. This is my first revolver so I can't tell just by feel...