I have a 12FV and an 11THXP. Both 1:9 barrels.
The 12FV shoots 77 Nosler CC bullets into 0.6-0.7" groups pretty regularly.
Both barrels will stabilize the 80 Nosler CC...but barely. I haven't gotten the 80's to group under 1.2" yet.
Neither will stabilize the 80 amax/eld.
The 11THXP put the 40 nosler varmageddon into 0.38"...

I say all that to say- common bullet spin rules are more like guidelines. Good to follow, but something outside the norm might also be good.

I like DIY. The barrel nut just makes sense. -PB