Working for a Police Department, I asked a swat team sniper how they break their' s in. He gave me the run down on it and I went to the range.

I fired a three shot group out of a new Browning Stainless Stalker (no boss) from 100 yards w/ Federal Premium ammo. It measured 1.220" .

I then started following his break in procedures which is basically;

Rounds 1-25
1 round - clean after each round.

Rounds 26-50
3 rounds - clean after each set.

Rounds 51-100
5 rounds - clean after each set.

Make sure barrel also cools between each set of shots.

After performing this pain in the butt task, the same ammo then shot 3/4" groups from that rifle. So, I think it does help if you want that kind of accuracy. I' ve followed that regimen ever since. Although I admit to not checking accuracy at the start with other rifles (wanted to get the break in over with).

Just my experiences and .02 cents.