The gun is selected by the USAF, not the contractor. (IIRC)

Is the cannon going to be GFE?
USAF I believe would approve/disapprove whatever cannon is selected by
the
prime contractor based on the requirements outlined in the contract that
was
awarded.

I really do not know. On ships all of the guns are GFE, on aircraft I do
not know.
I do know that the selection of weapons is a Govt decision, not the
contractors.

Approval of whatever selection is made by the prime contractor would be, but
according to the GD fact sheet on the JSF program the contract to design
produce and integrate the weapon for the JSF was awarded to GD by LMT, not
the US Government.

http://www.gdatp.com/products/lethality/jsf/JSF.pdf


They can award a sub-contract, but the decision as to what weapon to use
is up to the Pentagon.

Al Minyard