I would like to find out if the pin that holds the extractor is something that has to machined in or out of the gun. I've heard that it is nearly impossible to remove with a standard metal punch.

I don't plan on taking it out any time soon, but I like to keep extra parts around, that are prone to wear, for my guns and know how to replace them.

If anyone has removed one I'd really appreciate your input.

I have also heard that the solid extractor pins are tough to remove. Most newer production M&Ps have a roll pin which is easier to get out. My M&P9 is from 2009 and has the solid pin and I thankfully have not had to remove it. If I ever do remove it i'll probably soak the pin in Kroil for a few hours and hopefully a small starter punch and a solid tap from a hammer will dislodge it.

That's what I keep reading. That a 2mm short starter punch or a ground down 1/16th inch punch is required to get it started. Otherwise it will break a normal punch.

I've done it to a FS40.
It's a tough pin to remove, and as stated above, it can definitely break a normal punch (don't ask how I know). The small starter punch is what is needed. As always, wear safety glasses and be careful removing the extractor etc.