This aircraft in the Marine Corps and the USAF versions has encountered another big delay and setback. The USMC version was expected to enter combat service this year, 2015 and the USAF version in 2016. But, and this is a big but-the software support for the aircraft's onboard 25mm cannon will now not be ready until 2019, according to USAF officials. The F-35 program is over-budget and behind schedule. The F-35 will still carry missiles and bombs.