Is your buddy fairly familiar and comfortable with rifles and sighting them in?
I used to work at range and I was always amazed at how many frustrated guys there where sighting in their guns. Convinced they had bad guns, or scopes, or ammo. After observing a few, I couldn’t believe how quickly they were shooting. Even after just 3 rounds on a hot day, a hunting weight barrel on a 300WM can be too hot to hold. That can make it real hard to sight in.
I was also amazed how many setups had improperly torqued rings and/or bases.
Lastly to echo what others have said, if he’s not in a lead sled or similar, after a handful of 300WM rounds, most guys aren’t shooting great groups. One of my buddies was having a hard time and was convinced he Weatherby was only capable of 3-4in groups. I loaded an empty for him and when he pulled the trigger he jumped so bad that you’d thought it was a live round.
Be shot 3/4in group his first group in a lead sled.
It could be the scope, but it could and is likely a lot of other things. I’ve sighted in probably 50 scopes in my life ranging from $5 at a garage sale to $1,000 and I’ve never had one I couldn’t get zeroed.