I'd suggest getting the chisels out and inlet a barrel in a piece of soft wood from the box store. Get a 4x4 and you can do it 4x on each end. See how well or not well it comes out, do it a little better each time and pretty soon I think you'll be confident enough to do a plank for a rifle. I'd be surprised if you did it more than 3 times on the soft wood. I don't have anyone around here to learn from that I know of and I can't afford the time to go take classes, I read books, watch videos, and go slow. I make a lot of mistakes but going slow enough they are almost all able to be fixed before they are permanent. Power tools can remove the option to fix quickly so you can bet good money I am going to run the process a few times before I try it in good wood so I know how to get it done without destruction if I do use a power tool. I don't have any desire to produce in volume, so the slower process of doing a barrel inlet with chisels and scrapers only appeals to me, it's the opposite of my day job and a really nice change to do just one thing until it's done well.