Originally Posted by OptimumRC

I've had both of them rub, if yours didn't then it just happened to be luck I guess. After studying springs, I learned that the tendency of a spring to buckle is a function of the Spring free length /Spring diameter.

Hence why big bores springs are so much better. It's not the the spring is spaced further away but rather that the ratio (Free length / spring diameter) is less than four which is the ratio for its working stability. Measure this on a bb spring and AE spring and calculate it if you don't believe me, or look it up.