Although no longer a grower of autos, I have had virtually 100% germination with any Fast Buds seeds, just by growing them directly in soil and keeping them moist.
Big ones, little ones, it did not matter.
Quality of the plants was another matter all together.
You are doing something wrong, it seems, they have proven to be no harder to germinate than any other cannabis seed in my experience (40-50 Fast Buds seeds plus thousands of others).