These guns are exempted under section III on the BATF link...

Section III Guns
Luger, Artillery model, pistols having chamber dates of 1914 through 1918
or 1920, having German Weimar Navy markings consisting of the letter M
over an anchor and a German Navy property number accompanied by original
Artillery Luger flat board stocks, bearing German Weimar Navy markings
of the letter M over an anchor with or without Navy property numbers.

Luger, the 1920 Commercial Artillery model, pistols as mfd. by DWM or
Erfurt, having undated chambers, commercial proofmarks, and bearing the
inscription Germany or Made in Germany on the receiver and accompanied
by original, German mfd., artillery type, detachable wooden shoulder stocks.

Luger, DWM Pistol, model 1900, 1902, or 1906, in 7.65 Luger or 9mm parabellum
cal., having the American Eagle chamber crest, and barrel lengths of either
4" or 4-3/4, with original detachable Ideal shoulder stocks and Ideal
frame grips.

DWM Luger, Original models 1904, 1906, 1908, 1914 and 1920. Naval pistols
in 9mm parabellum or 7.65mm cal., in both the Commercial and Naval military
varieties; in both altered and unaltered barrel lengths in themodel 1904
and in both altered and unaltered safety markings in the model 1906; with
original board-type detachable shoulder stocks bearing brass or iron discs,
with or without markings, or, if without brass or iron discs, being of
the Navy flat board-type. This exemption applies only to the listed Naval
Luger pistols if mated to the Naval Luger stock and will not apply if
theNaval Luger pistol is mated to the Artillery stock. The Naval stock
has an overall dimension of 12-3/4", a rear width of 4-5/8",
a front width of 1-1/2", a rear thickness of 9/16", and a front
thickness of l-3/16".

Luger, DWM Stoeger model 1920 and 1923, semiautomatic pistols in 7.65mm
or 9mm parabellum cal., in barrel lengths of 8, 10, 12, and 12-1/2",
having either American Eagle chamber crests and/or Stoeger frame and/or
upper receiver marks, having either standard, Navy or artillery rear sights,
having extractors marked either "Loaded" or "Geladen"
and having frame safety markings of either "Gesichert" or "Safe,"
together w/original commercial flat board stocks of the artillery type,
which bear no S/Ns or military proof marks;may include a "Germany"

Luger, DWM Pistol-Carbine, model 1920, 7.65mm or 9mm parabellum cal.,
with accompanying original commercial type shoulder stock, with or without
forearm piece, having barrel lengths of 11-3/4" to less than 16".

Luger, German model 1914, Artillery model pistol, mfd. by DWM or Erfurt,
having chambers dated 1914 - -1918, bearing Imperial German military proofmarks
& accompanied by original, German mfd., artillery type, detachable
wooden shoulder stocks.

Luger, model 1902, Pistol-Carbine, 7.65mm Luger with original commercial
type shoulder stock and forearm and 11-3/4" barrel.

Luger, Persian (Iranian) Artillery model, pistols, as mfd. by Mauser prior
to 1945, accompanied by the original artillery type, detachable wooden
shoulder stock, bearing a S/N in Farsi characters stamped into the wood
on the left side.

Luger, semiautomatic pistol, certain variations with Benke-Thiemann folding
shoulder stock.

Mauser, commercial Luger Artillery model semiautomatic pistols cal. 9mm,
Mauser banner marked, produced under contract for the Royal Thai Police
accompanied by original, German mfd., detachable wooden shoulder stocks.

Section III-A Guns
Borchardt, model 1893, cal. 7.63mm pistol with accompanying shoulder stock.

Section IV Guns
Luger, Mauser commercial manufacture, semiautomatic pistol, 75 Jahre,
Parabellum-Pistol, Mod. Karabiner, Commemorative, caliber 9mm, accompanied
by a carbine type shoulder stock.