I was more just saying that if he only shot 100rd through it it likely wont matter when it comes to hunting accuracy.
If he never cleaned it, he likely DIDNT break it in properly in the first place.
Example. The people that built my rifle suggested to pull a bore snake with JB bore paste through the barrel after each 3 shots, Then pull a clean bore snake through. Do this for each three shot group the first 100 rounds.
If I decided that was too much work, and only pulled the snakes after every 10 rounds, or every 25 rounds. It likely won't make much difference with hunting accuracy...BUT, the manufacturer wont honor a 1/2 moa accuracy guarantee if I don't follow that procedure. (how they can tell, I have no idea)
Other manufacturers may say that's a terrible way to break in a barrel, some might say to just clean it good after 100 rounds.
It really depends on who's gun it is. If it was only a 1-2 MOA gun from the beginning, how you break it in probably won't ever change that for the better or worse.
