I'll try to take more pics tomorrow, but I don't have them now. Like I said earlier, my work isn't perfect, but it will do for now.
I started out with a Dremel cutting wheel, followed by a coarse sanding drum, then fine, then a grinding wheel, and then sandpaper on a small wooden block by elbow grease. I kept dunking the butt in cold water as I cut, but it still got hot. I figured it was far enough from the edge to not matter. It has just enough of a lip left to pop the top of a beer bottle.
I plan to strip the sage coating sometime soon. But I think I worked on this about 1.75 hours today, so that was enough for one day. Easy enough I'd do it again to another, but difficult enough it wasn't fun.
If you have a grinder to do the mod, that would be much better, IMO. I went through several cutting wheels doing this, since it wasn't all clamped in and everything. But ya gotta make do with what ya got.
It's not something I'd try to sell as pro. But I'm satisfied with my workmanship for now.