Hey Guys, I am new to this forum. Recently purchased a limited edition m4 with fixed skeleton stock. I am considering switching to something like the mesa urbino pistol grip stock for shorter LOP or going with the Benelli non-pistol grip stock.  What is the procedure for removing the lower part of the stock from the fixed recoil tube? Is this the same design/assy as the collapsable stock? When I press the button it wiggles but does not come off. The M4 is replacing a Benelli Nova, henc