Ok, I'll try to make this short and simple. A little over a year ago i bought a M&P sport ny legal. I have since moved to Vt. I would like to put a collapsable stock on the gun. I know I need a new buffer tube and spring. There seems to be some confusion on which one it is comm. Or mill spec. Can anyone help me out. Has anyone here made this conversion? Any info or sugesstions would be great, thanks Rick.