I saw this presented on beartooth bullets web site. Shooting soft lead with lapping compound to lap the rifleings. My gunsmith talks about wire brushing after 5 shots and so on.

What is the real dope on this? I have a new 35 whelen on a mauser action coming and just unwrapped a Ruger 1 in 45-70 to work up. Thanks for the advice.

What you're referring to is fire lapping. When you get a new gun there are imperfections and tool marks in the barrel from cutting the rifling into it. If you are getting a custum built gun the gunsmith will generally hand lap the barrel.
 
If you get a non custom gun, there has been no lapping of the barrel. There are those who believe that by shooting x-amount of bullets, the barrel is broken in and the imperfections are smoothed out somewhat. Then there's the fire lapping bullets you can buy and reload and there's also ammo already loaded with these bullets. The idea of course is to fire these bullets and smooth the barrel out until it's mirror smooth. Keep in mind that these take metal out and from what I understand, also lengthen the throat from material coming out. There are those who say it works and those who don't believe it does anything except take metal out of your barrel. I've also heard recommondations of you should only do it if your barrel is pitted or you're getting very poor accuracy.
 
I bought a few rifles this year and seriously considered it but ended up not doing it. I guess it falls to if you feel it will benefit you at all. My advice would be to first get the rifles and shoot them and see how they group and then go from there.

heres a nice 4-1-1 on barrel break in. http://www.larrywillis.com/Barrel.html