Product Overview

This is a newly manufactured 81mm U.S. M1 Mortar Cup (Receiver) designed specifically for live-fire applications. Precision-machined from 4140 HR steel, this component is built to meet the structural and dimensional standards required for reliable operation in one of the most historically significant mortar systems used by the United States military.

The mortar cup—commonly referred to as the receiver—is a critical component of the M1 mortar system, housing the firing pin assembly and absorbing the repeated impact forces generated during live-fire operation. This newly manufactured cup offers a dependable replacement for worn or damaged originals while maintaining the correct design characteristics of the historic U.S. M1 mortar platform.

Historical Significance

The U.S. 81mm M1 mortar was adopted by the United States Army in the late 1930s and became one of the most widely used infantry support weapons of World War II. The design was derived from the highly influential French Brandt 81mm mortar system, which established the basic configuration still used by modern mortars: a smoothbore tube, bipod mount, and baseplate.

During World War II, the M1 mortar served as the primary medium infantry mortar for U.S. forces across every theater of the war, providing essential indirect fire support for infantry units. It was capable of delivering high explosive, smoke, illumination, and training ammunition with reliability and accuracy, making it a vital component of battalion-level fire support.

The M1 mortar continued to serve beyond World War II, including during the Korean War, before being replaced by the later M29 81mm mortar system. Despite being succeeded by newer models, the M1 remains an iconic and historically important weapon system that helped define modern infantry mortar doctrine.

Manufacturing & Materials

This newly manufactured M1 mortar cup is machined from 4140 HR (hot rolled) alloy steel, a material selected for its strength, toughness, and ability to withstand repeated firing stresses. The use of 4140 alloy steel ensures the component maintains structural integrity during sustained use in live-fire environments.

Key manufacturing features include:

Precision machining for proper fit and alignment
Structural strength suitable for live-fire applications
Correct geometry consistent with the original M1 mortar receiver design
Durable alloy steel construction for long service life

Function of the Mortar Cup

The mortar cup (receiver) performs several essential roles within the M1 mortar system:

Houses the firing pin assembly
Supports and aligns the mortar tube
Absorbs repeated firing impacts
Maintains consistent primer ignition

Because this component bears significant mechanical stress during operation, proper material selection and machining precision are critical to function.

Key Features

New manufacture 81mm U.S. M1 Mortar Cup (Receiver)
Designed for live-fire applications
Machined from 4140 HR alloy steel
Correct geometry for M1 mortar systems
Durable, high-strength construction
Ideal for restoration, replacement, or operational mortar systems

Important Notice

If you have purchased a cup IE the “Receiver,” a barrel cannot be sent to you until an approved form 1 is received. It is not being sold as a registered destructive device. The cup, which is the receiver, must be shipped to an FFL licensee within your state. The cup will transfer as a standard Title 1 firearm receiver, no different than a standard rifle, shotgun, or handgun. You will go to your dealer and fill out the standard 4473 over-the-counter firearms transaction record. Once the receiver is in your possession, you must fill out and submit Form 1 (application to make and register an NFA firearm) to the BATFE, requesting permission to make a destructive device. Once you have received the approved Form 1 back from the ATF, you will provide us a copy of the Form 1 for our records. We will then be able to ship the barrel.

Must ship to an FFL license, as a Title 1 firearm receiver (no NFA transfer tax or paperwork required to go to FFL dealer). Be advised that it is a violation of ATF/NFA rules to possess a compatible 81mm cup (receiver) and a 81mm tube (barrel) at the same time without an ATF approved Form 1 or Form 4 for the 81mm mortar (or have a Type 10 Federal Firearms License) a barrel cannot be sent until an approved form 1 is received. See our terms and conditions for more information.

Why Choose This M1 Mortar Cup?

Original WWII-era mortar components are increasingly scarce, and many surviving receivers have experienced decades of wear or corrosion. This newly manufactured cup provides a reliable alternative for collectors, restorers, and operators who require a structurally sound component for a functioning M1 mortar system.

By combining historically accurate design with modern machining and materials, this mortar cup ensures your 81mm mortar platform remains both authentic and operational.

Order Information

Whether you are restoring a historic mortar system, replacing a worn receiver, or assembling a complete operational build, this new-made 81mm M1 Mortar Cup delivers the durability and reliability required for live-fire use.

Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.

See our Terms and Conditions here.

New Made 81mm M1 Mortar Cup

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