I require a bolt action platform for my suppressor and already have .300 BLK gear around. All ranges inside 200 yards and probably 7x glass.

I'm interested in converting a .308 Model 10 FCP to .300 BLK, using a barrel from Rhineland Arms (though I wish I could find one in 16"). The barrel swap seems straight forward... I think I understand the bolt head needs... But what about the magazine? Is the existing box mag expected to "just work" regardless of cal conversion?