Barrel Channel Work:

Get a wooden dowel the size of a broom stick (I actually use a handle for a sheetrock sanding block)

Warp the heaviest grit sand paper you can get around it, tape in place.

Work down, make sure lots of room.

I took a Pencil barrel Boyds and opened to a Bull barrel contour.

As noted, elbow work, heavier grit is the way to start as you take maximum material out. finer to finish up the channel.

Seal it with Formby's or some such.

EASB has a stock that you can get that is open to Heavy Varmint or Bull (a wait and extra).

It is Pilar posted, I had to work on mine to remove material to free float the receiver so there is no free lunch.

I don't know they have the mag setup you want.