Can 6mm Creedmoor brass be converted/resized to 6.5 Creedmoor?

[arakboss]

Question is in title. If the answer is yes, what is the best process to do so?

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[3MTA3]

I found this: https://www.ar15.com/forums/Armory/6-5-creedmoor-from-6mm-creedmoor-brass/42-494931/

Summary: first helpful post suggested case annealing, but OP didn't have one. OP later replied "To update, ran the 6mm CM brass through a 6.5mm Lyman mandrel die, which took the up to 6.5 CM with no complaints, and no split necks. Easy, and looks good."

 

[3MTA3]

I found this: https://www.ar15.com/forums/Armory/6-5-creedmoor-from-6mm-creedmoor-brass/42-494931/

Summary: first helpful post suggested case annealing, but OP didn't have one. OP later replied "To update, ran the 6mm CM brass through a 6.5mm Lyman mandrel die, which took the up to 6.5 CM with no complaints, and no split necks. Easy, and looks good."

Looks like this is a die designed for expanding necks - probably used the 260 Rem: https://www.lymanproducts.com/rifle-neck-expanding-m-dies

 

[Steel Head]

I don't see why not.
I used necked up 243 brass in my 260 for over a decade quite happily.

You can just use a good expander with good lube.
You can play it safe and use a 257 intermediate expander.

If brass is used definitely anneal it.