If you think so, try this.
There's a lot of misinformation still out there about cast bullets. I just read in a very nice, professionally made magazine that lead alloys rub off on the bore at high speed to cause leading. I thought I'd start a thread where folks could post experiences that run contrary to such conventional nonsense. I'll start with a few that grate on me, and open it up for anyone else to chime in that might want to.
If you think leading is caused by rubbing off in the bore, try this: Look down the barrel of high power pellet rifle. There will be no leading at all at over 1000 fps from the air rifle, but your 38 special will lead like mad from unlubricated lead bullets at 500 fps.
Try this too: Get a heavy steel plate and lay it so that it presents a flat surface at a shallow angle, facing down so there will be no richochet into the distance. Fire a bullet across the plate and go take a look at it. You will not find any adherent lead. You will only find a powdery lead smear that you can wipe off with your finger.
If you think that bullets can lead at high velocity because they 'run out of lube', try this: Shoot through a sheet of newspaper from a distance of 10 or 15 feet: You will find small flecks of lube thrown off by the bullet's spin all over it. Cast bullets have lube far in excess of any need, or there wouldn't be any left to spin off after it exits the muzzle.
Try this too: Saturate a bore mop with bullet lube and coat the bore for each shot. You'll find that the load that caused leading before will still cause leading, though there is no possibility that the bullet 'ran out of lube.
If you think that bullets can't strip the rifling, try this: Load a series of shots from very light to the highest velocity that the rifle will still shoot well. Shoot them into something that will allow you to recover the base of the bullet. Large bundles of loose cloth or paper will work well. Even fine sand will do. It will shatter the bullet nose, but the base is usually recoverable. Find the bullet after each shot and mark it. Lay them out side by side by side and look at the width of the engraving groove. You will find that (above a certain point) it gets wider and wider as the velocity increases. You'll also find that accuracy - and leading - becomes wild when the width of the engraving nearly covers the bullet.
If you think that leading isn't caused by etching from the hot propellent gas, try this: Fire a few mild rounds of cast bullets in your rifle that have no lube. After you've got that mess cleaned up, load a few more rounds with the same powder charge, the same unlubricated bullet, but put about 1/2 cc of Cream of Wheat under the bullet. (Keep it in place with a bit of cotton ball.) The cream of Wheat will firewall and keep the hot gas off the bullet. You'll find your bore remains bright, clean and competely lead-free.
Try this too: Take the bullet that is leading, and load it to the same velocity with a slower burning powder. Go from unique in your 357 Mag to 2400, and you'll go from bad leading to lead-free.
Try this too: Wrap that unlubricated bullet in a paper patch. The paper will also act as a firewall to keep the gas off the bullet. And again, you'll find that your bore remains bright, clean and completely lead-free.