Well, I guess that seals things...
No such thing as 'Over Stabilization'...
The spin either stabilizes the bullet, or it doesn't.
Instability due to spin is either too little or too much, underspin & overspin are acceptable.
The point is entirely purpose, APPLICATION.
She didn't say it would be a dedicated long range target queen, custom built for stupid heavy bullets.
She said she was looking for a rifle that would bang targets (since she's NOT stupid, that doesn't mean 1,000 yards), AND some hunting.
The current crop of precision rifles off the rack are 'Varmint' types, that means mostly 1:10" or 1:9" twist in bolt rifles, both will shoot hunting/varmint rounds and her supply of heavies, since they aren't stupid heavy and she isn't silly enough to try 1,000 yards with a .223 like a bunch of people I know *Claim* they do...
Her bullets will do a solid 600 yards, with EXACTLY the right load, *Might* even reach 800 yards.
Recommending some unicorn barrel that doesn't come off the shelf in a common rifle, or just the barrel eats up the budget is both pointless & confuses the issue.
I'm NOT talking MOA with this or that unicorn bullet, but standard Hornady bullets with common propellant & available primers shooting well under MOA,
I consider a 'Varmint' rifle suspect if I can't put 10 rounds under a nickel, and it's about right when 10 hit under a dime with commonly available components.
Since 'Varmint' rifles have a purpose, the available varmint rounds that make pinpoint accuracy possible ARE NOT available in stupid heavy weights, I can get behind that idea.
The idea of shooting a .223 1,000 yards to begin with is stupid.
There are a very select few that can shoot 1,000 yards, even less that can do it with a fully customized (read expensive) .223.
It becomes even more ridiculous when you can pull a $500 .308 (or a dozen other common chamberings) off the shelf and shoot 1,000 yards all day long without (expensive) modifications.
Again, correct application for the job. 223 is designed from the ground up to be pin point accurate (inherently accurate) at short to intermediate ranges to shoot VARMINTS with.
With proper ammo, it will pound 600 yards all day long, but energy at the target suffers no matter how heavy the bullet.
It wasn't built to punch paper targets at 1,000 yards so you can brag about your misapplication.
Don't get me wrong, I've built several, and I love those guys since they will dump buckets of money on my counter.
Then buckets more trying to find loads that will reach 1,000 yards,
And buckets more for optics that are accurate enough for 1,000 yards...
Before they figure out they aren't (and never will be) Wylde or Tubb.
People that just talk crap and don't understand the basics about what they read or heard just annoy me since they aren't paying me...