Elasticity using AS

Hi all. I want to put a bit of a ‘bounce’ onto this bit of code I have for an expanding cirlce. You know the kind of thing I mean. I want it to ‘pop’ open and then settle into an open circle.

m_Spot1.onEnterFrame = function() {
if (m_Spot1._xscale<200) {
m_Spot1._xscale += 35;
m_Spot1._yscale += 35;
}
};

Any help would be appreciated.