Back before all this current b.s. you could get Frontier 55gr h.p. match ammo for 33 pennies. Groups excellent, and lake city brass, would be perfect for fireforming. I should have bought a thousand.
I have a rem varmint barrel that never shot well, .8 moa after 250 rounds. I want to make it an ai for fire forming, and a fresh chamber might help it.
I agree it could look spacious. I like a lot of room around the barrel for cooling, I would get the sendero For a hunting contour. Op, plot out the diameter differences and decide what you want.