Sir Bob,
All bets are off on your powder charge for the new version of the 400-gr TBBC.
Totally new bullet is hopefully closer to 400 grains than the old one that weighed 390.5 gr., specimen of one.
New bullet is grooved and nickel-plated.
New bet:
Federal is using Alliant Power Pro Varmint in the new load.
You need to pull one of the bullets and weigh the powder and bullet for us please.
Safest "weigh" to do that is to weigh the loaded cartridge and subtract bullet weight and weight of primed case
after the powder is dumped = weight of powder. Just in "case" any grains go astray in the pulling process.
Or just be very careful to not lose any powder and weigh the powder directly.
I am sure you will get good pics of the new bullet and the powder grains.
For the new bullet, length of bullet (BOL) and the loaded ammo COL would be nice for posterity.
And while you are at it, what brass length did they use at the factory, 2.490"?
Finally, a chronograph reading when the risen creeks have gone down ?

Federal is still claiming 2250 fps MV for their 400-gr TBBC factory load.
Component bullets of that species are not available in their 2024 ammo catalog that I found at SCI Nashville yesterday.

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Ron aka "Rip" for Riflecrank Internationale Permanente
NRA Life Benefactor and Beneficiary
.458 Winchester Magnum, Magnanimous in Victory
THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.