Paint is paint. Any good quality spray paint will work as long as the stock has been cleaned and prepped properly. With Matte colors several light coats will look better than one heavy coat, and for more matte hold the can farther away.
Hunter Specialties makes a permanent flat black camo paint that works very well. I have done camo jobs on many bow and guns over the years with their paint and have never been disappointed. Just be aware that flat black will show wear and scratches easily, even if the job is done well with quality paint.
Hunter Specialties Flat Black Camo Paint