Bullet Impact Testing of Ammunition and Explosives at Picatinny Arsenal

A bullet impact (BI) test for evaluating the response of energetically loaded items has been established at the U.S. Army Combat Capabilities Command (DEVCOM) Armaments Center (AC) Explosive Development Facility.

A test gun mounted and aimed into the test chamber. (Image: Army Combat Capabilities Command)

Bullet impact (BI) is a standard test used to assess ordnance during insensitive munitions (IM) testing, for hazard classification, and for safety evaluations. IM evaluation and scoring features a series of tests designed to quantify the response of a munition to a variety of thermal and impact threats that are possible throughout its lifecycle, such as a fuel fire and impact from fragments and shaped charge jets. The BI test is designed to simulate a small arms attack.

This test is described in North Atlantic Treaty Organization (NATO) standards Allied Ordnance Publication (AOP)-39, “Policy for Introduction and Assessment of Insensitive Munitions (IM),” and AOP-4241, “Bullet Impact Munition Test Procedures,” and the United Nations “Recommendations on the Transportation of Dangerous Goods, Manual of Tests and Criteria.” It is required for all munitions developed and used by the U.S. military, as well as by NATO allies. The standard BI test (method 1) uses 12.7-mm (.50 caliber) armor piercing (AP) M2 cartridges with an impact velocity of 850±20 m/s. Three shots are fired at a rate of 600±50 rounds per minute at a 5 cm circular target area.

The munition’s response is characterized in AOP-39 using response descriptors on a scale of I (prompt detonation) to VI (no sustained reaction). The determination of the response requires extensive data collection, including cataloging and mapping the entire debris field, high-speed video, and dynamic pressure readings. The use of three bullets is to evaluate the munition’s response when subsequent bullets strike damaged material, which generally leads to a more violent response. However, the additional bullets tend to break open casings, which provides better venting, reduces confinement, and can result in a less severe response. The IM testing for official scoring is typically performed late in the munition’s development when the design is frozen, or nearly so.

Programs are encouraged to conduct subscale, engineering level tests early in development to identify vulnerabilities when solutions can more easily be implemented. To facilitate this, engineers from the U.S. Army Combat Capabilities Development Command (DEVCOM) Armaments Center (AC) Explosive Development Facility (EDF) developed an engineering-scale BI test capability for energetically loaded items. This test method is intended serve as a low-cost, highly flexible tool that can provide preliminary BI data at any point in the development cycle of a munition. It has the ability to precisely target specific locations and subassemblies of suspected vulnerability, such as fuzes and high-sensitivity booster explosives. However, this particular setup has several limitations that prevents its use for official IM scoring due to nonconformance with the prescribed test methodology and required data collection in the AOPs.

The confinement of the EDF’s test chamber precludes the ability to generate and characterize a debris field or collect accurate overpressure measurements, which are critical in accurately determining and scoring the response severity. Furthermore, the current test setup only enables firing of a single bullet into the test article, not the three bullets prescribed by AOP-4241. However, the results from this test setup should be sufficient to approximate the test article’s response in a full-scale IM test.

This test was implemented primarily as a method for evaluating the IM response of an energetically loaded item, but its utility is not limited to IM testing. The EDF possesses a wide range of advanced instrumentation and diagnostics that could be used to supplement traditional BI data collection. This report will describe the BI testing capability at the EDF, including a typical test setup and data collected, safety considerations that were implemented to minimize risk to personnel and equipment, and its limitations in fulfilling IM test requirements.

This work was performed by Steven Doremus, Erik Wrobel, Garrett Richards, Edward (Mike) Van De Wal, and Brian Fuchs for the U.S. Army Combat Capabilities Command Armaments Center.

For more information, download the Technical Support Package (free white paper) below. DEVCOM-08232

This Brief includes a Technical Support Package (TSP).
Document cover
Bullet Impact Testing of Ammunition and Explosives at Picatinny Arsenal

(reference DEVCOM-08232) is currently available for download from the TSP library.

Don't have an account? Sign up here.