I wouldn't try to sneak it past UPS as one is treading on Federal regulations regarding shipment of hazardous materials. From UPS's website:

UPS accepts for transportation such ammunition as constitutes "cartridges, small arms," as defined in 49 C.F.R. § 173.59. All other allowable ammunition shipments are accepted only on a contractual basis, and must be prepared under the rules for a fully regulated hazardous material.

Ammunition will be transported only when packaged and labeled in compliance with 49 C.F.R. § 172 (Hazardous Materials), and must be shipped in accordance with the UPS Guide for Shipping Ground and Air Hazardous Materials. To meet the exception for Limited Quantity/ORM-D, ammunition can be shipped via UPS Ground only within the 48 contiguous United States, UPS Ground Intra-Oahu and Intra-Alaska.

To qualify as "Cartridges, small arms ORM-D" or limited quantity, ammunition must be:

Ammunition that does not exceed 12.7 mm (50 caliber or 0.5 inch) for rifle or pistol cartridges or 8 gauge for shotgun shells; or
Ammunition with inert projectiles or blank ammunition
How to Package Cartridges, Small Arms
Ammunition must be packed in inside boxes, partitioned within a snugly fitting outside box or in metal clips. Cartridges must be properly cushioned and protected from accidental initiation. The inside boxes, partitions or metal clips must be packaged in securely closed outside packaging that will not open during transit. The package may not exceed 66 lb. (30 kg).

Is a Hazardous Materials Label or Marking Required?
Yes, (until December 31, 2020) packages that meet the definition of Cartridges, small arms must be marked with the proper shipping name "Cartridges, small arms", and designated as "ORM-D". Materials marked "ORM-D" and shipped by UPS Ground within the 48 contiguous states, UPS Ground Intra-Oahu and Intra-Alaska do not require hazardous material shipping papers. This marking may either be in the form of an ORM-D sticker, or written by hand. If written by hand the letters "ORM-D" must be enclosed by a rectangle that is ¼" larger on each side than the designation "ORM-D". (Note: The image below can be printed, cut out, and securely taped to the box with clear packing tape.)

ORM-D Cartridges, Small Arms
Alternatively, a black and white limited quantity marking (approximately 4 X 4 inches) may be used. (see example).

ORM-D Cartridges, Small Arms
Print the ORM-D or Limited Quantity marking and securely affix to your package. If using the limited quantity marking, please place on package as a "square on point" or "diamond".

Getting the Package to UPS
Cartridges, small arms 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: Cartridges, small arms are not accepted for shipment via UPS Drop Boxes, and may not be tendered to or dropped off at locations of The UPS Store® or any third party retailer or UPS Access Point™ location.

Domestic Cartridges, small arms shipments that meet the exception for Limited Quantity/ORMD packages and that comply with all UPS requirements for the shipment of ammunition (as set forth above, in the "Shipping Firearms or Ammunition" guidelines, and in the UPS Tariff/Terms and Conditions of Service and the UPS Rate and Service Guide in effect at the time of shipping ("UPS Terms")) may be delivered by UPS to a third party retailer or UPS Access Point™ location in the United States.

Will I Pay An Additional Fee For Shipping Cartridges, Small Arms?
When shipping ORM-Ds or Limited Quantities of hazardous materials by UPS Ground within the 48 contiguous states, UPS Ground Intra-Oahu or Intra-Alaska, only the standard shipping charges apply. There are no "accessorial" or additional charges.

Important Additional Information

Ammunition may not be packaged with firearms
Ammunition may not be shipped to individuals under the age of 18
Ammunition is not accepted for shipment internationally

For additional information regarding firearm and ammunition shipments, see "Shipping Firearms or Ammunition," at the link below, or contact UPS.

Shipping Firearms or Ammunition


UPS Tariff/Terms and Conditions (U.S)
All shipments tendered to UPS for service must meet the terms and conditions of service found in the UPS Terms. For specific information applicable to the shipment of ammunition, please follow the link below, download the UPS Tariff/Terms and Conditions of Service - United States and go to Section 3.6:

UPS Tariff/Terms and Conditions of Service

In This Section
49 CFR Shipping Examples
Shipping Ammunition
Related Information
ID8000 Consumer Commodity - Air Service (49 CFR)
Fully Regulated Material - Air Service (49 CFR)
Limited Quantity Exception - Air Service (49 CFR HM-215K)
Fully Regulated Material - Ground Service
Limited Quantity Exception - Ground Service (49 CFR HM-215K)
ORM-D - Ground Service
Small Quantity / Excepted Quantity (49 CFR)
49 CFR Special Provisions - Ground or Air
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