Rifled barrels are significantly more accurate than a smooth bore, they don't take "large chunks" of lead out of the bullet. They will how ever lead out over time and need to be cleaned. How many shots will depend on the rifle and load you use. When I say accuracy falls off in my gun I mean it won't shoot 2 inch groups or better at 100 yards anymore.

I don't shoot at running deer either, so I guess I'm the wrong person to ask. I rarely fire more than shot in a season at live game which is why I own a single shot shotgun and a ML.

As much as I hate to say it maybe buckshot would be a decent route for you.

Paul