Diehl Defence and BAE Confirm Long-Range 127mm Ammunition Integration with Mk 45 Naval Gun.

Diehl Defence and BAE Systems have agreed to cooperate on integrating Diehl Defence’s high-precision, long-range 127 mm ammunition with the BAE Systems Mk 45 Mod 4 naval gun for Germany and international customers. The initiative aims to provide Mk 45-equipped warships with an additional precision ammunition option for extended-range naval engagements.

Diehl Defence announced the cooperation on August 3, 2026, following a memorandum of understanding between the two companies. The agreement also covers potential integration of Diehl Defence’s IRIS-T family of guided missiles with BAE Systems launching systems, expanding the cooperation from naval gun ammunition to potential shipboard missile applications.

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Diehl Defence’s 127 mm high-precision, long-range ammunition is being considered for integration with BAE Systems’ Mk 45 Mod 4 naval gun under a new cooperation agreement targeting German and international naval requirements. (Picture source: Diehl Defence)

The first area of work will focus on the technical integration of Diehl Defence’s 127 mm, or 5-inch, ammunition family with the Mk 45 Mod 4. According to the announcement, the companies intend to advance the specific technical work required to combine the naval gun with Diehl Defence’s high-precision, long-range ammunition.

Neither company has disclosed the designation of the 127 mm ammunition involved, its maximum engagement range, guidance method, warhead characteristics or a timetable for qualification. The August 3 announcement therefore establishes the integration objective without providing detailed performance specifications for the ammunition.

The Mk 45 Mod 4 is a 127 mm naval gun developed by BAE Systems for surface combatants. The Mod 4 configuration uses a 62-caliber barrel and is designed to provide naval gunfire against surface and land targets while supporting the use of more advanced ammunition.

Integration of precision long-range ammunition would broaden the types of engagements that Mk 45-equipped warships could conduct with their main gun. Greater accuracy and extended reach can increase the effectiveness of naval gunfire against targets at sea or ashore while providing commanders with an additional weapon option alongside ship-launched missiles.

The cooperation also has international relevance because the Mk 45 family is used by the U.S. Navy and several allied naval forces. Qualification of an additional 127 mm ammunition family could therefore create opportunities for Diehl Defence among existing and future Mk 45 customers, depending on national requirements and subsequent certification.

For BAE Systems, the cooperation could expand the ammunition options available for the Mk 45 Mod 4. For Diehl Defence, integration with an established 127 mm naval gun could provide access to a wider international customer base and strengthen its position in the naval ammunition market.

The initiative is particularly relevant for navies seeking to increase the flexibility of shipboard firepower. Modern surface combatants must address targets ranging from small vessels and larger surface combatants to coastal positions and other threats, creating demand for weapons capable of delivering different effects at different engagement distances.

Precision 127 mm ammunition can provide another option within that weapon mix. Depending on the capabilities ultimately demonstrated by Diehl Defence’s ammunition, the Mk 45 Mod 4 could be used for precision engagements in situations where commanders do not need to employ larger ship-launched missiles.

The agreement also reflects growing attention to naval ammunition availability and magazine depth. Surface combatants carry finite numbers of missiles, while their naval guns provide a separate ammunition inventory that can support repeated engagements during sustained operations.

The second element of the memorandum concerns the IRIS-T guided missile family. Diehl Defence and BAE Systems will explore the potential integration of IRIS-T missiles with launching systems from BAE Systems, although the companies have not identified the missile variant or launcher configuration being considered.

The absence of those details means no specific naval IRIS-T configuration has yet been announced. Further technical work will be required to determine the missile, launcher and integration architecture that could be offered to German or international customers.

Any future shipboard missile integration would also require compatibility with the vessel’s combat-management system, sensors and fire-control architecture. The final operational capability would therefore depend on the specific IRIS-T variant, launching system and ship configuration selected.

The cooperation comes as Germany and other NATO members continue strengthening naval combat capabilities and ammunition availability. It also connects Diehl Defence’s German missile and ammunition expertise with BAE Systems’ established naval weapon systems and international customer base.

For Germany, the agreement could support closer industrial cooperation while increasing opportunities to integrate German-developed weapons with equipment already operated by allied navies. This approach could also improve interoperability by expanding the range of compatible weapons available across different fleets.

The memorandum does not constitute a procurement contract, and neither company has announced a customer order, integration timetable, live-fire qualification program or planned entry into operational service. These milestones will determine how quickly the cooperation develops into a deployable naval capability.

The next important step will be the technical integration and qualification of Diehl Defence’s 127 mm ammunition with the Mk 45 Mod 4. Confirmation of its range, guidance technology and intended target set will provide a clearer indication of the additional combat capability the ammunition could bring to Mk 45-equipped warships.

In parallel, further details concerning the IRIS-T effort will determine whether the cooperation develops into a new shipboard air-defense solution. Together, the two projects could broaden the weapon options available to German and international naval forces while strengthening industrial cooperation between Diehl Defence and BAE Systems.

Update: Army Recognition Group (ARG) has corrected an earlier version of this article that incorrectly associated the 127 mm ammunition covered by the Diehl Defence and BAE Systems cooperation with Leonardo’s Vulcano ammunition. There is no stated relation between the ammunition addressed in this cooperation and Leonardo’s Vulcano ammunition. The article has been updated to reflect the information officially released by Diehl Defence on August 3, 2026. We regret the error.

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Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.