[mrerick]

It would seem to cover any handgun or rifle, including "technical information" about them....

The State Department definition of "firearms is in:

https://www.pmddtc.state.gov/regulat...R_Part_121.pdf

Here's an excerpt:

473 Department of State § 121.1
ENUMERATION OF ARTICLES
§ 121.1 General. The United States Munitions List.
CATEGORY I—FIREARMS, CLOSE ASSAULT WEAPONS AND COMBAT SHOTGUNS
* (a) Nonautomatic and semi-automatic firearms to caliber .50 inclusive (12.7 mm).
* (b) Fully automatic firearms to .50 caliber inclusive (12.7 mm).
* (c) Firearms or other weapons (e.g. insurgency-counterinsurgency, close assault weapons systems) having a special military application regardless of caliber.
* (d) Combat shotguns. This includes any shotgun with a barrel length less than 18 inches.
* (e) Silencers, mufflers, sound and flash suppressors for the articles in (a) through (d) of this category and their specifically designed, modified or adapted components and parts.
(f) Riflescopes manufactured to military specifications (See category XII(c) for controls on night sighting devices.)
(g) Barrels, cylinders, receivers (frames) or complete breech mechanisms for the articles in paragraphs (a) through (d) of this category.
(h) Components, parts, accessories and attachments for the articles in paragraphs (a) through (g) of this category.
(i) Technical data (as defined in § 120.10 of this subchapter) and defense services (as defined in § 120.9 of this subchapter) directly related to the defense articles enumerated in paragraphs (a) through (h) of this category. Technical data directly related to the manufacture or production of any defense articles enumerated elsewhere in this category that are designated as Significant Military Equipment (SME) shall itself be designated SME.

The following interpretations explain and amplify the terms used in this category and throughout this subchapter:
(1) A firearm is a weapon not over .50 caliber (12.7 mm) which is designed to expel a projectile by the action of an explosive or which may be readily converted to do so.
(2) A rifle is a shoulder firearm which can discharge a bullet through a rifled barrel 16 inches or longer.
(3) A carbine is a lightweight shoulder firearm with a barrel under 16 inches in length.
(4) A pistol is a hand-operated firearm having a chamber integral with or permanently aligned with the bore.
(5) A revolver is a hand-operated firearm with a revolving cylinder containing chambers for individual cartridges.
(6) A submachine gun, ‘‘machine pistol’’ or ‘‘machine gun’’ is a firearm originally designed to fire, or capable of being fired, fully automatically by a single pull of the trigger.

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The exclusions listed at the end of the section are:


NOTE: This coverage by the U.S. Munitions List in paragraphs (a) through (i) of this category excludes any non-combat shotgun witha barrel length of 18 inches or longer, BB,pellet, and muzzle loading (black powder)firearms. This category does not cover riflescopes and sighting devices that are not manufactured to military specifications. It also excludes accessories and attachments (e.g., belts, slings, after market rubber grips, cleaning kits) for firearms that do not enhance the usefulness, effectiveness, or capabilities of the firearm, components and parts.

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Since "Military" is not defined to exclude historical firearms (not in the current arsenal) these rules likely apply to Lugers and anything else a military has used.