My BCM M4 stock will be arriving soon, I know I need an AR15 armorer tool to remove my factory A2 stock and install the M4 one. I haven't checked my buffer tube yet to see if it's Milspec or Commercial. My M4 stock is Milspec and has a M4 castle type nut. Is there a specific tool you guys would recommend? I have read several reviews on tools that claim the tools aren't fitting the nuts and have to be ground to fit; my local gun shop has a DPMS tool for about $35.00 but I want to get a good tool not a POS...and this is my first AR, so I don't know much yet.