2010ish M2 reduce lop?

[Nerevar7]

Hello all, 

looking for a reliable guide or method for reducing about half an inch from the default lop comfort tech early 2010 M2 stock.

Nominally this method would retain the original pad as it's what I've always used and it's been pretty good right out of the box from day one, except I have to "reach " just" a wee bit to wrap the right index finger around the trigger comfortably.  Probably shite for form but it seems to work well enough. But it does get uncomfortable as you can imagine.

if it's not really feasible to remove some lop and keep the original pad I'd also appreciate a recommendation for pads folks have used and enjoyed.  I know it may not be the most suited shotgun for breaking clay on the weekend with the buddies, but that's what I use it for, if that impacts anyone's recommendation.

I apologize if this is a common request in this forum, I tried searching with and without tags and didn't get any results either way. Thank you.