Long guns, whether rifle, shotgun or muzzleloader(antique by USPS regs), are mailable as long as they aren't NFA weapons.
UPS doesn't differentiate between firearms and muzzleloaders, they accept them all including handguns, but have restrictions on where they can be accepted for shipment and handguns must be shipped overnight service.
Regulations from both services are below.
Tim
http://pe.usps.com/text/pub52/pub52c4_008.htm43 Firearms
431 Definitions
431.1 Firearm
A firearm is defined as any device (including a starter gun) that is designed, or may readily be converted, to expel a projectile by an explosion, a spring, or other mechanical action, or by air or gas pressure with sufficient force to be used as a weapon.
431.2 Handgun
Pistols, revolvers, and other firearms capable of being concealed on the person (for example, short–barreled shotguns and short–barreled rifles) are defined as handguns. The following definitions apply:
a. Pistol or Revolver. A pistol or revolver is a handgun designed to be fired by the use of a single hand.
b. Short–Barreled Rifle. A rifle having one or more barrels less than 16 inches long is defined as a short–barreled rifle. This includes any weapon made from a rifle (by alteration or modification) resulting in an overall length of less than 26 inches.
c. Short–Barreled Shotgun. A shotgun having one or more barrels less than 18 inches long is defined as a short–barreled shotgun. This includes any weapon made from a shotgun (by alteration or modification) resulting in an overall length of less than 26 inches.
431.3 Antique Firearm
An antique firearm (including one with a matchlock, flintlock, percussion cap, or similar type of ignition system) is any firearm manufactured in or before 1898, or a replica of such a firearm, that meets either of the following conditions:
a. It is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition.
b. It uses rimfire or conventional centerfire fixed ammunition that is no longer manufactured in the United States and that is not readily available through commercial trade channels.
431.4 Rifles and Shotguns
A rifle is a shoulder weapon having a barrel that is 16 inches or more in length. A shotgun is a shoulder weapon having a barrel that is 18 inches or more in length. Rifles and shotguns have an overall length of 26 inches or greater and cannot be concealed on a person.
431.5 Licensed Manufacturer or Licensed Dealer
A manufacturer of firearms or a bona fide dealer in firearms is one duly licensed by the Bureau of Alcohol, Tobacco, and Firearms (ATF), U.S. Department of the Treasury, under the Gun Control Act of 1968.
http://pe.usps.com/text/pub52/pub52c4_009.htm432 Mailability
432.1 General
The following conditions apply:
a. Pistols, revolvers, and other firearms capable of being concealed on the person (referred to as “handguns”) are nonmailable in the domestic mail, except as permitted in Exhibit 432.1 and DMM 601.11.1.
b. The disassembled parts of a handgun or other type of nonmailable firearm that can be readily reassembled as a weapon are nonmailable, except as permitted in Exhibit 432.1 and DMM 601.11.1 or 601.11.2.
c. Unloaded antique firearms sent as curios or museum pieces are generally permitted, as specified in Exhibit 432.1 and DMM 601.11.2.
d. Unloaded rifles and shotguns may be mailed if the mailer fully complies with the Gun Control Act of 1968 (Public Law 90—618) and
18 U.S.C. 921. The mailer may be required to establish, by opening the parcel or by written certification, that the gun is unloaded and not excluded from mailing because of the restrictions in 432.1b and c.
Exhibit 432.1
Mailability Requirements for Firearms
Unloaded Handgun
Handguns — e.g., pistols, revolvers, and other firearms capable of being concealed on the person — are nonmailable UNLESS mailed by a licensed manufacturer of firearms, or a licensed dealer of firearms, or an authorized agent of the federal government or government of a state, territory, or district, and ONLY when addressed to a person in one of the following categories for use in the person’s official duties AND upon filing the required affidavit or certificate, as applicable (see DMM 601.11.1.3–7):
a. Addressee: Officer of Army, Coast Guard, Air Force, Navy, Marine Corps, or Organized Reserve Corps.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the commanding officer.
b. Addressee: Officer of National Guard or militia of a state, territory, or district.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the commanding officer.
c. Addressee: Officer of the federal government or a state, district, or territory whose official duty is to serve warrants of arrest or commitment.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the head of the agency employing the addressee.
d. Addressee: Postal Service employees specifically authorized by the Chief Postal Inspector.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the head of the agency employing the addressee.
e. Addressee: Officer or employee of a U.S. enforcement agency.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the head of the agency employing the addressee.
f. Addressee: Watchman engaged in guarding federal, state, district, or territory property.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by chief clerk of department, bureau, or independent branch of the government agency employing the addressee.
g. Addressee: Purchasing agent or other designated member of an enforcement agency employing officers and personnel included in c, d, or e above.
Affidavit or Certificate Requirements: Mailable with affidavit signed by addressee and certificate signed by the head of agency stating the firearm is to be used by an officer or employee cited in c, d, or e above.
h. Addressee: Licensed manufacturers and dealers of firearms.
Affidavit or Certificate Requirements: Signed statement on PS Form 1508, Statement by Shipper of Firearms.
The mailer must be a licensed manufacturer or dealer mailing to another licensed manufacturer or dealer.
Handguns may be mailed without regard to the requirements noted in items a–h if the addressee is the FBI (or its Director) or a scientific lab or crime detection bureau of any agency whose members are federal law enforcement officers, or state, district, or territory officers authorized to serve warrants of arrest or commitment.
Manufacturers or dealers must complete PS Form 1508, Statement by Shipper of Firearms, and file with the postmaster.
Postmasters may forward an unsatisfactory mailer statement to their PCSC for a ruling.
Unloaded Rifle or Shotgun
Short-barreled rifles or shotguns that can be concealed on the person are nonmailable.
The mailer must comply with the Gun Control Act of 1968 and with state and local laws.
The Postal Service may require the mailer to open the parcel or give written certification that the weapon is unloaded and not concealable.
Registered Mail service is recommended.
Unloaded Antique Firearm
Unloaded antique firearms sent as curios or museum pieces are acceptable for mailing.
432.2 PS Form 1508
PS Form 1508, Statement by Shipper of Firearms, must be completed by each firearm manufacturer or dealer who deposits firearms for mailing. The form must be filed with the postmaster of the post office of mailing.
432.3 Packaging and Marking
No markings of any kind that indicate the nature of the contents may be placed on the outside wrapper or container of any mailpiece containing firearms. Mailable matter must be properly and securely packaged within the general packaging requirements in DMM 601.1–8.
http://pe.usps.com/text/pub52/pub52c4_010.htm433 Mailer Responsibility
Even though certain types of firearms are permitted to be mailed within the provisions of the postal law in 18 U.S.C. 1715, it is the mailer’s responsibility to comply with all federal and state regulations and local ordinances affecting the movement of firearms.http://pe.usps.com/text/pub52/pub52c4_011.htm434 Legal Opinions on Mailing Firearms
Postmasters are not authorized to give opinions on the legality of any shipment of rifles or shotguns. Mailers should be referred to the nearest regional ATF office for further advice (see AFT Online at www.atf.treas.gov).
http://www.ups.com/content/us/en/resources/ship/packaging/guidelines/firearms.htmlShipping Firearms
Special Procedures for Shipping Firearms
Use These UPS Services for Your Firearm Shipment
UPS accepts packages containing firearms (as defined by Title 18, Chapter 44, and Title 26, Chapter 53 of the United States Code) for transportation from and between licensed importers, licensed manufacturers, licensed dealers, and licensed collectors (as defined in Title 18, Chapter 44 of the United States Code), law enforcement agencies of the United States (or of any department or agency of the United States), law enforcement agencies of any state or department agency (or political subdivision of any state), from and between persons not otherwise prohibited from shipping firearms by federal, state or local law, and when such shipment complies with all federal, state and local laws applicable to the shipper, recipient, and package.
* Handguns, as defined by 18 U.S.C. § 921,will be accepted for transportation only via UPS Next Day Air Services, specifically, UPS Next Day Air® Early A.M.®, UPS Next Day Air®, and UPS Next Day Air Saver®. (Note: UPS Express CriticalSM Service is not available for firearms).
* UPS accepts firearm parts for shipment, provided the part is not a "firearm" as defined under federal law; the contents of the package cannot be assembled to form a firearm; and the package otherwise complies with federal, state, and local law. (Note: Receivers or frames of a firearm, firearm mufflers and silencers are considered "firearms" and are accepted for transportation only if shipped in accordance with UPS's requirements for shipping firearms.)
* UPS does not accept automatic weapons, including machine guns, for shipment.
* Firearms (including handguns) and firearm parts are not accepted for shipment internationally.
* UPS ReturnsSM Services are not available for packages containing firearms.
Follow These Packing Requirements
* Packages containing handguns must be separated from other packages tendered to UPS for delivery.
* All firearms are to be shipped in new corrugated packaging which meets the UPS Single Wall Box Strength Guidelines. Medium and large UPS boxes may be used for smaller shipments being shipped via UPS Express service.
* All firearms are to be packaged in accordance with UPS Packaging Guideline Specifications.
* Ammunition must be shipped separately from packages that contain firearms (including handguns).
* Ammunition will be transported only when packaged and labeled in compliance with 49 C.F.R. § 172 regarding hazardous materials shipments, and must be shipped in accordance with the UPS Guide for Shipping Ground and Air Hazardous Materials.
About Documentation and Labeling
* The shipper must use Delivery Confirmation Adult Signature Required service for each package containing a firearm, including a handgun, and affix a UPS label requesting an adult signature upon delivery.
* The labeling and outer box markings on all firearms shipments should not identify the contents as containing a firearm. Labeling, including the shipper's and consignee's abbreviated names on the shipping label or air shipping document, must be non-descriptive.
Getting Your Firearm Shipment to UPS
* Firearms (including handguns) may be shipped only through a UPS Scheduled Pickup Account (specifically, Daily Pickup, Daily On-Route Pickup, UPS Smart Pickup, and Day-Specific Pickup), or through a UPS Customer Center (counters at UPS operational facilities). Note: Firearms (including handguns) are not accepted for shipment via, UPS Drop Boxes, UPS On-Call PickupSM, or at locations of The UPS Store® or any third party retailer. * When you are shipping a package that contains a handgun, you must verbally notify the UPS driver or UPS Customer Center clerk.
* See the terms and conditions in the UPS Tariff/Terms and Conditions of Service for information regarding firearm shipments.