The different springs close the gap between not firing and firing as gently on paint as possible. It’s been a while, but here’s what I remember when using largest carrier that doesn’t leak, well oiled, gun in good working order, etc.
Gold spring will start firing around 225fps. If you turn the gun up to shoot 285fps, there is excess force behind the bolt. Excess meaning it won’t be as gentle on paint as possible, but it will be ultra-reliable due to the 60fps differential.
Red spring will start shooting around 250fps. If you turn the gun up to 285fps, there’s enough force behind the bolt to fire, but it will be gentle on paint. 35fps differential - this is ideal for reliability and gentleness on paint.
Long gray spring uncut starts shooting around 300fps. This one is meant to be trimmed for fine-tuning at the risk of the gun occasionally not firing.
Originally, I used a tight carrier and trimmed gray spring. It was incredibly gentle on paint, but the gun was not reliable. I remember hitting the side of the gun and degassing/regassing the gun to get it to work while taking fire from multiple angles. I changed to red spring and largest carrier that wouldn’t leak. I could still pinch the same ball 5-10 times before it would break, and the gun was reliable.
Last of the Salzburg Clan