Jack, The letter that I mentioned can be found in this transcript:
Hearings Before the Subcommittee To Investigate Juvenile Delinquency of the Committee on the Judiciary

United States Senate

Ninetieth Congress

2nd Session,

Pursuant to, S. Res. 240, Ninetieth Congress, on S.3961, S.3604, S. 3634, S. 3637, June 26, 27, 28 and July 8, 9, 10, 1968.

A copy of the Gun Control Act 1968, along with the Subcommittee hearings, testimony, and accompanying information such as the letter should be available from your Congressman.

Getting a copy of the Nazi Weapons Law 1938 is not difficult, but I hope you can understand German. If I recall, the JPFO use to have a translated copy.