Getting down to bare metal shouldn't be that hard. It's never been fired, right?

Even if it has been fired a lot, you can use some Hopped #9 to get the powder fouling out, WipeOut to get the copper out, and then a patch wrapped around a brush, smeared in JB Bore paste to get every last bit of fouling out of the barrel. Rinse with Hoppes, and you should be GTG.