If you are referring to the spring on the AA chamber, its only there to apply back pressure to the arm to push it against the adjuster. Other than that, it doesn't do anything. Any instability will stem from the nub itself and imperfect mating surfaces. Without the spring you are relying on the bucking to do that, which could be detrimental to your bucking's health and longevity.
I don't mean any offense by this, so don't take it that way. I think it's hilarious that people are hell bent on building a better rifle, custom making parts, then not understanding why the spring in the AA chamber is there. If you are going to improve something, then you need to really look at what each part does and its full functions and what it experiences during use. Then you need to answer, "Why was this designed this way?"