Is this going to be a competition target gun? If not the difference is going to be so small to be unnoticeable to the average joe. If this is going competition target then it would be better to purchase an aftermarket competition barrel then take a saw to a stock barrel. The harmonics of a barrel is only important if you are going to fine-tune a round for it, the perfect bullet, powder, etc. and make it the same every time. Most factory ammo is not made to nearly tight enough tolerances to matter. For large caliber competition shooting, many guys will make (or have made) each bullet by hand on a lathe to get the exact standards they require.
So short answer... barrel length MOSTLY (99.9%) only effects bullet velocity. If your buddy shoots 1" groups at 100 yards, he is still going to shoot 1" groups at 100 yards. There is a lot more to this than just the length too, is it bedded (and if so, how?), is it floated, what lug is he using, etc etc. If he wants to cut (or doesn't) based on accuracy, then don't worry about it. 2" won't matter enough.
Mike (and his .02)
So short answer... barrel length MOSTLY (99.9%) only effects bullet velocity. If your buddy shoots 1" groups at 100 yards, he is still going to shoot 1" groups at 100 yards. There is a lot more to this than just the length too, is it bedded (and if so, how?), is it floated, what lug is he using, etc etc. If he wants to cut (or doesn't) based on accuracy, then don't worry about it. 2" won't matter enough.
Mike (and his .02)