If you put a heavier barrel on it, consider installing a rimless extractor and chamber for one of the .22 or .20 caliber rimless cartridges with a .223 case head size. Chamber wall thickness at the barrel threads is the limiting strength factor, not the action it's self
I've got to agree with Der Ami here. With so many choices available in rimmed cartridges of appropriate head diameter for this action why complicate things by going rimless unless you are really looking for a challenging winter project to occupy your time.
