Just googled fire-crake & the only gun-related reference to it that I could find was in a novel by Sir Arthur Conan Doyle entitled 'The White Company', which is set during the Hundred Years War. It certainly sounds like it is an artillery piece of some sort. Here's the quote from the book:
And how could man die better?" asked the archer. "If I had my wish, it would be to fall so--not, mark you, in any mere skirmish of the Company, but in a stricken field, with the great lion banner waving over us and the red oriflamme in front, amid the shouting of my fellows and the twanging of the strings. But let it be sword, lance, or bolt that strikes me down: for I should think it shame to die from an iron ball from the fire-crake or bombard or any such unsoldierly weapon, which is only fitted to scare babes with its foolish noise and smoke."
"I have heard much even in the quiet cloisters of these new and dreadful engines," quoth Alleyne. "It is said, though I can scarce bring myself to believe it, that they will send a ball twice as far as a bowman can shoot his shaft, and with such force as to break through armor of proof."