that's the beauty of western arms airsoft pistols.  The one I did was a SCW2 (2nd gen), the original actually has a firing pin that the hammer strike and in turn nail the valve that releases gas.  By changing to a stiffer hammer spring, you'd really see big impact on the output.  Versus this one and subsequent ones where a hammer spring doesn't much that big difference anymore.  I wish I can own a real one.