Good article.... yeah, I found myself cringing when he took a carbide burr to the rifling... but hey, all in the name of scientific inquiry.

It goes to what I was saying. Every barrel deforms the bullets... it squeezes them down, presses rifling marks into the jackets, and scrapes the heck out of the jacket with every defect and machining mark in the bore. But what matters is that it will mangle and kick all the bullet the same way. So the mangled chunk of metal that emerges from the bore is going to fly the same way as the one before it. Gross defects may cause shifts in point of aim/point of impact between wildly different loads, but so long as every bullet is getting the same abuse, accuracy is still possible, even if the bullet is no longer even close to the shape the manufacturer intended.

That said, it is always nice to eliminate variables whenever possible. So it is still worthwhile to have a decent crown on the barrel, just to cross it off the list of variables.

There is also a psychological aspect to this... something that looks right to the shooter inspires confidence in the shot. If the crown looks right, then the shooter stops worrying about it and focuses attention elsewhere, like actually executing the shot well. I liken it to folks who fixate on the fit of the upper and lower receiver in an AR-15. A tight fit doesn't do anything to help the accuracy of the rifle, but it helps the shooter feel better about the rifle. You can pound the X ring with a AR that rattles just as efficiently as with one that is tight... all you have to do is get past the feel of the thing rattling and focus on the shot you are about to make.