Here in Froschreich, the legislation is a bit more relaxed - they have two classes of ammunition - military calibre and civilian calibre. The distinction is in fact not based on performance, but simple availability; military ammunition in common WW2 calibres is/was generally not too hard to find on the alternative market, while ammo in civilian calibres has to be obtained from a gunshop, which leaves a paper trail. Many WW2 weapons have been re-barrlede to take the closest civilian rounds. The problem is that blanks are not available in these calibres, although you could I suppose make your own.
All my rifles and SMGs have been legally "castrated" - a shame, I know, but one which enables me to take them out to shows and so on without too much hassle.
Just as well - a neighbour - we are NOT friends - denounced me to the Gendarmes for my collection of bits and pieces - they came round, were very polite and friendly (the Gendarmes are military, unlike the normal French Police, who are total ar*eholes) and had an hour of fun playing with the toys! They also failed very diplomatically to notice that one, which I got rid of subsequently, was not neutralized...
Finally, the No.IV MkI in the photo is not mine - I've got a No.I MkIII which was made in Australia in 1944.