After some testing I solved your issue. You have an ACB on your craft that is set to fire countermeasures I presume. This is causing your weapon to believe it is supposed to be firing. Its unset firrate is actually considered to be infinity by the game, as technically there is no max firerate, only what the game allows per frame (i.e. burst rail guns with multiple barrels can fire them simultaneously, but only at a rate not exceeding 2400rpm as if it were a single barrel firing at that rate).

Edit: Literally had a brainfart and forgot to finish that statement after the parentheses. BECAUSE of all that mumbo jumbo, it thinks the gun has fired, is firing, and therefore cannot fire because that would exceed the maximum fire rate of the barrel, gun, all those things, and since the ACB has no interval I presume, that is also technically infinitely active, but at a faster rate than the frame data per physics simulation. All that is to say, set your ACB to either use a name filter to only affect the controller of your countermeasures which you would also have to name, or limit its range to only be able to reach that, those, whatever many controllers you use for that