Interesting.

Do you think a custom rifle shoots poor ammo better than a factory stick?

Or do you think the ammo is the limitation in most instances, and you have to have both a rifle that shoots well AND ammo with good concentricity to get 7- or 10-shot MOAish groups?

FWIW, I believe most rifles will shoot MOA for 3-shot groups, but I don't think that tells me much about a rifle.