Just count out the minimum numbers a printer will take to make a copy of your book detract that price from your book price and voila do your own calculation.
I think it's about 2000 copies.
I know one dude who's written books on shotguns and declared himself a self proclaimed expert just by reading other people's book and adding pictures of his own and then writing books himself.
Result with afaik 2000 copies sold out.
That dude is a clueless muppet honestly and I could explain with proof..., just pm as I'm in a total arsey mood of late, and who will only get followed by other clueless muppets as he's writen a book....
Market for airguns is a bit less.
If the book is of value which I'm guessing it is then it should sell.
I'm not sure if Mr Griffiths self published or not but I haven't seen any copies of his book come up for sale for yonks on amazon...go figure.
It only means you need to put in x amount of your own money.
Draw your own conclusions.
Just some musings from a book fanatic.
Atb