Resize 450/400 3 1/4 to 450 3 1/4?

[analog_peninsula]

Is there any functional reason why I shouldn’t try to run the 450/400 brass through the 450 expander? Inquiring minds want to know.

 

[Mark A Ouellette]

Is there any functional reason why I shouldn’t try to run the 450/400 brass through the 450 expander? Inquiring minds want to know.

That's a pretty big expansion that might split the cartridge case neck. Better aneal that very well.

A better path may be to first aneal the case necks then fire form using a small charge fast burning powder and some type of lightweight filler in lieu of a projectile.

 

[Bandera]

I agree with Mark A on the procedure.
Other than a split case give it a go.
There are people who resizing 308 win up to 375 to create the 375 Raptor.
Most likely the thickness of the brass will dictate if it would work reliably.

 

[Wyatt Smith]

It will probably come out short, not sure if that will be an issue for you

 

[rookhawk]

Is there any functional reason why I shouldn’t try to run the 450/400 brass through the 450 expander? Inquiring minds want to know.

Not sure if it will work. You'd probably want custom sizing dies to step it up 3x gradually, annealing as you go. As Wyatt stated, not sure if you'll have the needed length.

Maybe much easier is just getting 450NE brass? It would save you a thousand bucks on special dies. 450/400 3.25" is more valuable, harder to find brass than the 450NE brass anyway.