I think your dad's probably talking about the abrasive bullets that are supposed to lap the bore when you fire them. I don't know about you, but I wouldn't put sandpaper on a jag and scrub my bore with it, let alone fire a sandpaper coated bullet down the bore at 3000+ fps. Doesn't seem like a smart idea to me.

As for break in, there are a dozen different RIGOROUS break-in regimens that I've heard people swear by, and I've tried some of them and never seen any improvement in results worth the extreme effort (IMO). I've heard of guys that scrub the bore spotless after every shot for the first 25-50 shots. That's a lot of work, and I think that it defeats the purpose with a factory bore.

As said above, clean the bore before you shoot it, taking care to remove all oil as well. Then what I do is just a light cleaning every 3 shots for about the first 20-30. By light I mean no scrubbing with a bore brush. Just a good multipurpose bore solvent (I like Birchwood Casey's Bore Scrubber) on a patch, run it through to wet the bore, let soak for a few minutes (3-5), then run clean patches until dry. What you're trying to do it get the powder fowling and EXCESS copper fouling out. If it's a factory bbl the bore will be pretty rough, the copper wash fills and smoothes these areas as you shoot. You want to put down just enough copper to fill the rough spots and no more, and you don't want to fill them with powder deposits, hence the cleaning process. If you overdo the cleaning and strip out all the copper, you're back to square one with a rough bore that will tend to fowl quickly. If you do it right, the barrel will build up just the right balance of copper and will shoot well and still stay consistantly clean shot to shot. I've seen small improvements in both accuracy and consistency using this approach (1/4 to 1/2" improvement in group size at 100 yards), but the biggest thing is that you won't build up tons of copper fowling later on.