It is still up in the air whether the US Marine Corps will have combat-ready Lockheed Martin F-35 Lightning IIs by its July 1 deadline for initial operational capability (IOC), but the first 10 jets are now fully cleared to fire weapons.

The portion of the 2B software that manages weapons separation has completed the necessary testing, the Pentagon’s Joint Program Office (JPO) announced on 15 January. The F-35B’s software was validated after several weapons separation tests

“The weapons development program continues to track forward on the plan laid out by the technical baseline review approved in 2010,” Lt. Gen. Chris Bogdan, F-35 programme executive officer, says in a statement. “All weapons tests needed for 2B software, the software the US Marine Corps will use to declare IOC, is complete and will be ready to go for their combat capability certification.”

The Marine Corps still plans to go IOC on 1 July, a deadline it has chased so fervently that the service agreed to field 10 jets with the less-capable Block 2B software. The US Air Force's first F-35As will be fielded with the intermediate 3i configuration, which incorporates a new helmet and mission processors using 2B software, and finally with Block 3F after that final software configuration is fielded as early as 2017. Older jets will be retrofitted with 3F at a later date.

Whether the Marine Corps’ F-35Bs will become operational by the 1 July deadline remains uncertain. Lockheed and the JPO are scrambling to catch up on a month of lost software and flight testing resulting from an engine fire that temporarily grounded the fleet.

High-ranking US officials, including JPO chief Lt Gen Christopher Bogdan, Navy Secretary Ray Mabus and Air Force Chief of Staff Gen Mark Welsh have in recent weeks doubled down that the Marines Will have operational jets on or near July 1.

Live fire ground testing of the F-35B was completed in early September, the JPO says. In October, the F-35B was certified to perform day and night close air support missions with the 2B software.

Separations testing with a 113kg (250lb) Boeing GBU-39 small diameter bomb was completed 20 November. The aircraft also completed flutter testing with the MBDA AIM-132 short-range air-to-air missile and Raytheon Paveway IV laser-guided bombs in late 2014.

An F-35 also fired two MBDA AIM-120 AMRAAM missiles and a Boeing joint direct attack munition (JDAM) during weapon delivery accuracy tests, marking the first supersonic guided missile launch. It also was the first time the F-35 has hit a target with a JDAM using coordinates generated by the electro-optical targeting system (EOTS).

The announcement comes on the heels of controversy over reports that software necessary to operate the conventional takeoff and landing F-35A’s main 25mm gun, the General Dynamics GAU-22, would not be ready until years after the service declares IOC in 2016. Reports indicated the gun would not be operational until 2019. The JPO insists the gun will be operational when the final Block 3F software comes online in 2017.

Comprehensive flight test on the F-35A’s 25mm gun system is scheduled to begin mid-year at Edwards AFB, California, and will include ground fire tests, muzzle calibration, flight test integration and in-flight operational tests, the JPO says.

The Marine Corps’ F-35B and navy’s F-35C have no internal gun. Marines will have the option of carrying the GAU-22 in an externally mounted pod.

The 25mm missionized gun pod carried externally, centerline mounted on the F-35B and F-35C also begins testing this year to meet U.S. service’s desired schedule for full warfighting capability software known as 3F. The 3F software is currently planned for delivery with the low rate initial production nine (LRIP 9) US aircraft in 2017.

Both the A and C models completed weapon milestones in 2014. The F-35C launched an AIM-120 AMRAAM, the last separation test needed to certify the variant’s Block 2B software.

The F-35A finished the final buffet, load and high-angle of attack testing necessary for its Block 2B software.