The banter about the VSR system being designed for 1 joule is only half true. While the Tokyo Marui VSR 10 was designed to fit that bill, VSR clones like the JG BAR10 or Cyma VSR target higher energy markets. That being said, they will still require you to upgrade the triggers, as they are inadequate even for the stock spring. Both platforms will still require a bit of work. Your best friend with the VSR 10 will be customizability and cylinder volume. Even if your original stock isn't adjustable, you can always buy an aftermarket one that is. Why do you need an adjustable one, might I ask?