25-mm Cartridges
Bushmaster 25mm ammunition provides the firepower necessary to meet a variety of applications for the Bradley Fighting Vehicle, the LAV, other infantry fighting vehicles, and air defense platforms (equipped with the McDonnell Douglas M242 chain gun, the Oerlikon KBA B02B1 weapon system, or any other NATO-qualified 25mm weapon system). Other derivatives of the Bushmaster 25mm family, such as the PGU series of cartridges, are used in the AV-8B Harrier (PGU-25 HEI) and in the AC-130 Gunship (PGU-38 HEI). Variants such as the MK 210 HEI-T and PGU-32 are used in shipboard defense systems like the MK 38. All rounds are interchangeable with the M242 Bushmaster gun, the KBA B02B automatic cannon, the GE525 (GAU-12/U) Gatling gun, and other NATO-qualified systems.
The LAV-25 is an all-terrain, all-weather vehicle with night capabilities. It provides strategic mobility to reach and engage the threat, tactical mobility for effective use of fire power, fire power to defeat soft and armored targets, and battlefield survivability to carry out combat missions. It is air transportable via C-130, C-141, C-5 and CH-53 E. When combat loaded there are 210 ready rounds and 420 stowed rounds of 25mm ammunition as well as 400 ready rounds and 1200 stowed rounds of 7.62mm. There are 8 ready rounds and 8 stowed rounds of smoke grenades. A supplementary M240E1 7.62mm machine gun can be pintle-mounted at the commander's station in the turret. The LAV-25 is fully amphibious with a maximum of 3 minutes preparation.
During the first week of April 2003, the 29th Infantry Regiment Bradley Master Gunner Branch had an in depth briefing with representatives from TACOM-ARDEC, PM Bradley, DOT, TSM-S/B and S/BPO in reference to the nose cap and double feed issue for 25-mm sabot ammunition. This briefing was broken into two parts, the first part discussed Double Feeds with the 25-mm chain gun and the second part was specifically about nose caps being cracked and potentially causing gun jams.
The ability to double feed a round and potentially initiate the primer of a previously chambered round is not possible during normal cycle (firing) of the 25-mm chain gun based on the anti-double feed feature, the Positive T-slot Extractors. It is very unlikely that a round can be double fed during remedial action of a 25-mm malfunction however the risk of a double feed is specifically introduced when the Straight Drive Shaft is lowered and crews attempt to clear a malfunction by moving the feeder and receiver independently. Again, the round is still positively controlled by the Positive T-Slot extractors until it has been placed in the ejection chute. It is this point that a round could possibly fall back in front of the bolt, forward of the T-Slot Extractors. Now the round can be chambered without being controlled or forward of the T-Slot Extractors by rotating the Straight Drive Shaft as if you were attempting to clear a malfunction. Then as a crew uses their hand crank to rotate the feeder assembly back to SEAR, they place a new round on the face of the bolt positively controlled by the T-Slot extractors and behind the chambered round. Again, the previously mentioned scenario is very difficult to create, however the possibility does exist.
The Nose Cap issue is tied to Double Feed prevention but not as a direct result or cause. What is happening to the nose cap is cracking caused by the plastic sabot swelling and contracting resulting from temperature change during storage. Currently there are only two "confirmed" reports of weapons failure due to nose caps coming off causing a 25-mm gun jam. The first was from the Armament Tech Facility while using the M791 APDS-T and the 2nd was from the Kuwait National Guard while using the M910 TPDS-T. The conclusion was that it is possible for 25-mm sabot ammunition to cause a gun jam if the nose cap comes off while entering the Breech Assembly. Nose caps can sometimes prevent the 25-mm from cycling through FEED resulting in a malfunction that cannot be reduced with normal misfire procedures alone. The Master Gunner or crewmember needs to physically separate the Feeder Assembly from the Receiver Assembly and inspect the Breach, Barrel, and Receiver Assembly(s). Current recommended actions in the event of a nose cap jam is to follow hot gun procedures by waiting 30 minutes before separating the weapon system. Identifying a nose cap jam is more difficult than correcting one. However, if the 25-mm gun malfunctions while the BPI is in the RAM position (just before fire) chances are you have a nose cap jam.
Crew-members should be informed that if a nose cap falls off of the round DO NOT try and put it back on. However, at the same time do not attempt to remove all cracked nose-caps from 25-mm ammunition. Some would think by removing all cracked nose caps the risk of a nose cap jam would be mitigated, however, it may increase the likelihood that the solid windscreen would act as a firing pin and initiate the primer of an already chambered round in the event of a double-feed.
There was no easy modifications that could be performed to the current 25-mm sabot ammunition family that would support the second anti-double feed feature or the nose cap-cracking problem. TACOM-ARDEC is exploring solutions to this issue; these solutions could find their way into the M910E1, a future Sabot ammunition ballistically matched to M919, currently in the design phase. Until then, the school-house will incorporate this Double Feed Awareness into the 25-mm class and Nose Cap Cracking Awareness into our Ammunition Capabilities Class. However the risk to mitigate the above event falls directly on the Master Gunners and leadership in the field.
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In February 2002, Altarum began a study to determine the feasibility of a common caliber for the OICW and the OCSW Programs. On March 29, 2002, Altarum presented the "Objective Crew Served Weapon Caliber Study" to the Joint Service Small Arms Program. The study recommended that: a common ammunition or round for each weapon was not feasible; however, a common projectile (internal workings of the fuze and warhead) would be feasible; the two weapon systems should utilize the same fuze setting, range determination, and safe and arming mechanism; and the two weapon systems should have similar 25-milimeter ammunition.
Although Altarum determined that using similar 25-milimeter ammunition for the OICW and the OCSW would increase the weight of the OICW, it determined that using similar ammunition would allow a reduced cost per OICW ammunition and would increase OICW lethality. Altarum also determined that the OCSW fuze was cheaper to manufacture than the OICW fuze by $5.48 per fuze. After the study, the PEO Soldier was to determine whether further commonality could be accomplished between the two systems to reduce life-cycle costs and logistics support.
On March 19, 2003, the Procurement Contracting Officer, Picatinny Center for Contracting and Commerce, U.S. Army TACOM Life Cycle Management Command,2 on behalf of the Project Manager Soldier Weapons, directed Alliant Techsystems to cease work on the XM29 20-millimenter ammunition.
On June 2, 2003, the procurement contracting officer directed Alliant Techsystems to begin work developing a 25-millimeter weapon system and ammunition. Alliant Techsystems was to change the caliber, fuze setting, and range determination of the XM29 and to become a member of a combined XM29 and XM307 integrated product team to develop 25-millimeter ammunition. Also on June 2, 2003, another procurement contracting officer at the Picatinny Center for Contracting and Commerce issued a letter to General Dynamics Armament and Technical Products, Inc. (General Dynamics), the prime contractor for the XM307 Program. The procurement contracting officer requested that General Dynamics explore possible arrangements with Alliant Techsystems for collaboration in the development of a 25-millimeter family of common ammunition designs. The procurement contracting officer also stated that the Government determined that a family of 25-millimeter projectiles using maximum commonality of components and design was the optimal path for proceeding with the XM25/XM29 and the XM307 Programs.
On January 16, 2004, the procurement contracting officer, who issued the June 2, 2003, letter to Alliant Techsystems, redirected Alliant Techsystems' efforts away from developing a common fuze technology. The procurement contracting officer directed Alliant Techsystems to restart its fuze setting and range determination efforts that it had been pursuing before the June 2, 2003, letter. According to a representative from the OICW Program Office, the redirection of the common fuze technology occurred because efforts to maximize ammunition commonality between programs was not successful. The primary reason was that Alliant Techsystems and General Dynamics could not come to a teaming agreement regarding proprietary data exchange.
In April 2006, a representative from the XM307 Program Office stated that he doubted whether a common round would be developed for the XM25/XM29 and XM307 Programs because: the contractors could not come to an agreement, a considerable amount of time elapsed during which each program continued to develop its own design, and recent program status and funding implications make this a "very dangerous strategy."
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