This one is a 24 inch barrel, I would not stub a 20-06 into a H&R stub, I don't think you could get the chamber thickness you need. It would make an excellent rechamber for a .204 Ruger H&R barrel, it is dead easy. I also learned a little trick tonight, nto totally Handi related, but in loading up the first batch of 20-06 ammo I discovered that, if you take the expander ball out of the sizing die, it makes an excellent crimp die. Just put the loaded round in the sizing die and pull it down until it firmly bumps the neck, you end up with the nicest crimp you have ever seen. Larry