Don't cut the barrel. Just have your friend do the following:
1. Check this link out for better barrels, different guages and even rifle slug barrels:
http://www.hr1871.com/Support/accessoryProgram.aspx
2. Install a recoil pad
3. Only after your friend has every barrel he may want or need, file a tiny notch in the receiver to line up with the single bead site (accuracy improvement). Don't do this and then expect them to fit a new barrel.