Unliscenced firearms can be handed in to a registered Firearms dealear, who may be wiling to help with De-Activation. Especially if the weapon is of 'Historic intrest'. Obsolete calibre exemption can be a bit tedious. I know where a mixed rifle/shotgun was declared obsolete on one calibre, but not the other. As that weapon was also of historic intrest and in the care of one of the country's leading gunsmiths, you see the problem. A WW1 German Rifle, to me means either a Mauser 1895 or 1898 , neither are considered obsolete calibre. Regardless, unless it Proof House marked deactivated and certified in writing in the view of the law it is live!