The wording of the ITAR:
Category III—Ammunition/Ordnance
*(a) Ammunition/ordnance for the articles in Categories I and II of this section.
(b) Ammunition/ordnance handling equipment specifically designed or modified for the articles controlled in this category, such as, belting, linking, and de-linking equipment.
(c) Equipment and tooling specifically designed or modified for the production of defense articles controlled by this category.
(d) Components, parts, accessories, attachments and associated equipment specifically designed or modified for the articles in this category:
*(1) Guidance and control components for the articles in paragraph (a) of this category;
*(2) Safing, arming and fuzing components (including target detection and localization devices) for the articles in paragraph (a) of this category; and
(3) All other components, parts, accessories, attachments and associated equipment for the articles in paragraphs (a) through (c) of this category.
(e) 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 described in paragraphs (a) through (d) of this category. Technical data directly related to the manufacture or production of any defense articles described elsewhere in this category that are designated as Significant Military Equipment (SME) shall itself be designated SME.
(f) The following explains and amplifies the terms used in this category and elsewhere in this subchapter:
(1) The components, parts, accessories and attachments controlled in this category include, but are not limited to cartridge cases, powder bags (or other propellant charges), bullets, jackets, cores, shells (excluding shotgun shells), projectiles (including canister rounds and submunitions therefor), boosters, firing components therefor, primers, and other detonating devices for the defense articles controlled in this category.
(2) This category does not control cartridge and shell casings that, prior to export, have been rendered useless beyond the possibility of restoration for use as a cartridge or shell casing by means of heating, flame treatment, mangling, crushing, cutting or popping.
(3) Equipment and tooling in paragraph (c) of this category does not include equipment for hand-loading ammunition.
(4) The articles in this category include any end item, component, accessory, attachment, part, firmware, software, or system that has been designed or manufactured using technical data and defense services controlled by this category.
(5) The articles specifically designed or modified for military application controlled in this category include any article specifically developed, configured, or adapted for military application
I’ve put the important parts in bold.
Para (c) and an explanation in para (1) basically covers everything from round components to all parts and tools of reloading machines. So basically, everything associated with home loading (including a ruler if you use one).
Para (3) gives the dispensation of home loading. So as long as it’s home loading and not commercial manufacturer you are good to go. Hazardous goods (primers, primed cases and powder is a separate transport issue).
I’ve brought back 10,000 of thousands cases, bullets, dies and reloading machines from the states. Every time they have been inspected by TSA and permitted to go.
Hope that helps.