The current software on the F-35 doesn't support a gun.
It's supposed to be deployed with the next software but they're having problems with it.
When the door that hides the gun to keep the F-35 stealthy opens, it jerks the plane making it miss.
The gun only has 220 rounds and just a few seconds of firing time. And not all models even get that.
Jerks can cause a lot of trouble...
Very expensive toast!