Personally rather than reinvent the wheel to save a few bucks, especially on a tool designed for life saving measures I think I'd stick with the factory replacement stuff myself. Order a few for your friends so the shipping cost isn't so offensive.
The springs in the over all scheme of things are not that expensive, seldom need to be replaced and just having a spare is excellent insurance.
The gun will indeed tell you when it's time.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."