Ahem, I really did have a Mini-14 that would do MOA. Unfortunately I believed it to be illegal in California, and sold it before I moved there (they weren't
)
And I have seen one 5.56 AR that honestly would do only 3.5MOA before I replaced the barrel. And a .300 Blackout that would do 1.75MOA only with handloads.
But in general, I think the AR on average will outshoot Minis, and will be a more ergonomic rifle. I still have an old Mini, and one day I'll do some more work with it.
