O' both of them barrels should last as long as 6 seconds.
http://bulletin.accurateshooter.com/...s-barrel-life/




Barrel life is approximate, each barrel has its own personality, and some last longer than others. Some things that influece barrel life is type of barrel, (Cut rifled VS button rifled.) Use of moly or other coatings, cleaning, and there is even a formula to predict barrel life and it has something to do with the amount of powder burned.

I have seen barrels that just dont give up the ghost, and have the throat, and rifing gone, one barrel I remember belonged to Sharp shooter it had 4000 (22/250) round down the tube torchered in a dog town, that was rebarreld to a 22 br, there was nothing to the barrel for the first 6 inchs past the chamber (No lands groves just clean.) and that barrel would shoot 5 shoot 100 yard groups in the .2 to .3 area all day long.

On cleaning the most important thing it to get as much of the hard carbon out that you can, and they only way I have ever seen to do this was with a bronze brush, and a good solvent.