Barrel break in is an interesting topic. We've done a lot of testing and can tell you that it absolutely matters. The gray zone is what approach/procedure to use and how many rounds. We’ve worked with Proof and we tend to agree with their recommendation. Use this sequence for initial barrel break in and prior to an accuracy test.
1. Shoot 3 shots, then clean
2. Shoot 3 shots, then clean again
3. Shoot 5 shots, then clean again
From here, we've found that you can generally shoot normally, cleaning only as needed. We have noticed that accuracy tends to continue to improve through the first 80 rounds. Proof doesn't assess accuracy until 80 rounds. We would say contact us if the rifle is not grouping after 40 shots.
Proof lists known cleaning products and they are all perfectly acceptable (). For those who favor milder cleaners something like ThoroughClean and ThoroughFlush work well.