The barrels don't wear out due to friction.The throats burn out due to pressure and heat.

Yes, barrels do wear from friction. Takes awhile, but rifling can and is shot out. Throat wear also occurs, at least that part of your statement is semi-correct.

Large-cased overbore cartridges that burn huge quantities of powder to achieve their velocities are going to wear throats faster than smaller-cased cartridges of the same caliber. The 7mm Ultra Mag, 7mm STW and 7.21 Fireball are a good deal faster than the 7mm Rem. Mag., but they burn a whole lot more powder to get there. Overall barrel wear will be faster, and they will erode throats much faster.

Agreed.

You can burn out a throat,set back the barrel and start again with virtually the same accuracy.This can be done several times before barrel wear would ever become a factor.Barrels for cartridges known to be barrel burners were often made from stainless,not because it is more resistant to wear,but because it is more resistant to throat erosion.Barrel wear due to friction will never be a factor as throat erosion will occur at a much faster rate.

Barrels still wear due to friction. Not just the throat, which definately wears faster, but the entire barrel.

If wear due to friction were a factor,the wear would be greatest at the point of greatest velocity and therefore the greatest friction.That would be at the muzzle not the throat.How many barrels have you personallyseen that were worn out at the muzzle?Every scrapbarrel that I have seen at my gunsmiths were replaced due to throat erosion.

Stone Axe Engineering Throat Erosion & Muzzle Wear Gauges by Mike Conroy
I could see that his face suddenly had some frustration to it. He came over and asked me, "Just what the hell are you doing?" I told him that I measured the muzzle wear and the throat erosion of the barrel that he claimed was in "very good condition and was a good shooter."As it turned out, the barrel on his "good shooter" had a muzzle wear of "6" and it's throat erosion was at "7". I then told him that his asking price of $850 was outrageous. He didn't like to hear that and with that, I walked away. On a scale of 1-10, with 10 being the worst, you can see were this barrel measured up to. It was basically a "shot-out" tomato stake. More

http://www.stoneaxeengineering.com/[/align]

If you actually go to the link and read the use for the wear guages ,you will see that they are made onlyfor military weapons.Military weapons are exposed to entirely different conditions than hunting rifles such as steel jacket ammunition or incendiary rounds or extreme abuse due to combat conditions.Modern sportingammunition and normal conditions are an entirely different situation than military usage,so the wear conditions will be very different as well.

However to see some other peoples opinions on the subject ,I startedtwo threads ontwo sites thatare more dedicated to shooting and reloading.Hereare the links so you can see what others have to say on the matter.

http://forums.accuratereloading.com/groupee/forums/a/tpc/f/9411043/m/170100593

http://www.24hourcampfire.com/ubbthreads/showflat.php/Cat/0/Number/687135/an/0/page/0/gonew/1#UNREAD