HK416 Closed Bolt outer barrel issue

[CplHicks]

I've recently picked up an older WE HK416 with uses the closed bolt system. Problem is I'm unsure as to whether the outer barrel can be shortened from 14.5in to 10.5in. I don't want to damage the rifle, does it unscrew like the Open bolt version, or will I have to replace the barrel with a shorter OB one?

Thanks all