Austria is a CIP member and Proof of Firearms is required just the same as in the U.K., as far as I am aware so, if altered would be an offence to sell. I suggest you contact your Proof House in Austria for advice and possible examination. https://www.bing.com/search?q=proof+hous...mp;qs=n&sk= This link may help. Good luck. Lagopus.....