C&R firearms are defined in Title 27,
Code of Federal Regulations, Part 478.11 as those "of special interest to collectors by reason of some quality other than is associated with firearms intended for sporting use or as offensive or defensive weapons." To be recognized by ATF as a C&R firearm, a firearm must fall into at least one of the following three categories: C&R firearms include most manually operated and semi-automatic firearms used by a military force prior to . This includes most firearms used by the warring nations in
World War I and World War II. However, the firearm must normally also be in its original configuration to retain the C&R designation. So, for example, an unaltered
Mauser Karabiner 98k rifle used by the
German Army in World War II is a C&R firearm – but the same rifle "sporterized" with new stock and finish is generally not considered a C&R firearm. There is an ambiguous point in how the license is currently administered, in that some firearms altered by the militaries that issued them have been confirmed by the ATF to retain C&R status, though whether this applies to
all such conversions (the examples given by the ATF were the Spanish M1916 Guardia Civil, FR-7, and FR-8 Mausers) also remains ambiguous. However, as long as the
receiver (the part of the firearm that is regulated by the ATF) is over 50 years old, the firearm qualifies as a Curio & Relic – ATF states explicitly that, in addition to newer firearms it individually approves, firearms automatically achieve C&R status upon turning 50, provided they are in the original configuration. If modified significantly, the 50-year clock resets to the date of modification. (Specific examples are available in the ATF FAQs.) Certain automatic firearms have been designated as C&R firearms, and a C&R may be used to acquire these as well. Collectors may acquire C&R firearms in interstate commerce, e.g., via mail or phone order or the Internet, or in person. (This is especially important for collectors of pistols and revolvers since they may not otherwise be acquired outside a collector's state of residence.) Collectors are not considered to be FFL dealers and have no special privileges concerning non-C&R firearms, nor may they "engage in the business" of regularly selling C&R firearms to persons who do not have an FFL. Selling of C&R firearms does not require an FFL transfer across state lines, only if the firearm has a collectible status. The purpose of the C&R license is to enable a collector to acquire C&R firearms for their personal collection and not to become a firearms dealer.
Curio & relic compliance inspections (D) At the election of a licensed collector, the annual inspection of records and inventory permitted under this paragraph shall be performed at the ATF office designed for such inspections which is located in closest proximity to the premises where the inventory and records of such licensed collector are maintained. : —
ATF 2005 Regulations page 18. (ATF Publication 5300.4)
Conversion of C&R firearms Any firearm sold as a C&R firearm once changed out of its original configuration cannot be resold as a C&R firearm. In regard to conversions; certain pistols have been approved for sale with added safety conversions (i.e. Polish and Romanian
Tokarev pistols, to which a manual safety was added to meet import requirements). Certain other modifications, such as period sporterisations, are arguably C&R qualified as they represent the gun culture of the period. An example would be a
Lee–Enfield or
98K Mauser military rifle that had been converted into a continental style sporter before World War II. These common conversions occurred more than 50 years ago, and represent a sub-type of special interest to collectors.
Antiques Federal law defines guns manufactured in or before 1898 with unconventional firing mechanisms (such as percussion, flintlock and other combustion methods typically considered "black powder"), or cartridge firearms that have uncommon and not readily available ammo types (.30-40 Krag, .30 Mauser,
.44 Russian, etc.) as "antique" (26 USC §5845(G)), (27 CFR §478.11) and they are generally unregulated in federal law. They may be bought and sold across state lines without an FFL. The only exceptions are short-barreled rifles, short barreled shotguns, and machine guns, which are regulated under the
National Firearms Act of 1934. Unlike C&R guns, antique guns can be re-arsenalized, sporterized, re-barreled, or re-chambered, yet they will still retain their federally exempt status. Even if every part except the receiver is replaced, a pre-1899 "black powder" firearm still qualifies as an antique. FFL holders have been directed not to enter Pre-1899 guns into their Bound Books. ==Record keeping==