These striker springs are interchangeable with all 13XX and 22XX models and can be very effective for changing performance characteristics.
The DISCOVERY SPRING is the new version Crosman/Benjamin started using in 2017. It's shorter and stiffer than the original. It produces a more consistent shot string with less hammer bounce. It's very durable, it will soften slightly as it breaks-in then stay at that performance level for years. It's about 1-5/8" long with a wire diameter of .042". The older version is obsolete and I no longer have them in stock.
The Discovery spring is commonly used to boost the power of 13XX and 22XX models. A power adjuster is recommended, this allows you to fine-tune spring tension for the best balance of FPS, accuracy and efficiency. There's a peak performance point you can find using an adjuster. Beyond that peak point can cause the valve stem to rebound faster which reduces power.
The 22XX SPRING has a wider range of adjustment than the 13XX version when used with a power adjuster. This is because 22XX version is smaller wire diameter and has fewer coils. The 13XX SPRING is a little stronger when used without an adjuster. The 22XX spring is 2" long and .031 wire diameter. The 13XX is 2" long and .034 wire diameter.
2300T and 2300S have the lightest of all these hammer springs. It really only works well for those models which have a sleeve and longer spring guide inside the valve to limit the power level.
Stronger hammer-spring tension increases trigger pull. It also makes it harder to pull the bolt back. It will pull back easier with your finger hooked around the front of the handle close to the breech. It usually works the smoothest when done in one quick motion. Using a power adjuster helps reduce trigger pull, adjust to the minimum tension needed to produce the FPS needed.