[m1903a3]

While I agree with Olie that it's unlikely a random ATF agent would know or care, the real danger is if you somehow get on their radar for other reasons. At that point you are at risk of them having an NFA violation to beat you with. Also, bear in mind that if you possess either an Army or Navy stock (or exact replica) you better have a P.04 or lP.08, whichever is appropriate, to go with it. Under the law merely possessing the stock and the wrong Luger with a stock lug is illegal, you don't actually have to mount it. As long as you have the correct Luger for the stock you're ok, just don't use it with a different Luger.

Also. all Navy stocks don't have medallions. The early ones were shipped without them. Subsequently, when the Navy order the use of medallions, most of the early one were fitted with one. But, just as with the order to modify the safeties, some were never altered.