I got me a front sight post tool to help me adjust the post height.   The one I got is made by Tapco.  Works perfectly on my Bushmaster FSB.  However when I try to use it on my S&W M&P FSB or the upper I got from Spike's Tactical it doesn't seem to disengage the release pin and allow me to turn the post.  Basically useless.  I would have thought the sight posts were fairly universal but appears not to be the case.  Is there that much differences between A2 FSBs or is there a better sight tool out there?