Doesn't look like it would chamber at all, as the shoulder on the .223/5.56mm is MUCH farther forward than the Valkyrie. Not to say a person couldn't slam the bolt over and over until it deformed the round and locked, but obviously that's not a reasonable/safe option, nor do I recommend it...

 

Valkyrie's parent case is 6.8SPC which makes it completely different than 5.56
They do have bullets in common but that is it.
Different bolt, completely different chambers.
Oh and different magazine.

So to answer your question....not a snowball's chance in hell.
224V sounds like a great cartridge.
https://www.americanrifleman.org/ar...g/articles/2017/10/30/the-keefe-report-224-valkyrie-rightly-the-next-big-thing/

 

The shoulder of the .223/5.56 is almost .300" longer (forward) than the .224. Diameter at the base of the case is approx .050" larger in diameter on the .224 vs the .223/5.56. You'll know if you load a .223/5.56 in a .224valk and vice versa.

 

Thanks, that is what I was thinking.