Seeds of a F1 hybrid are not guaranteed to revert to type, but the chance of them doing so is massively higher than any other types.
So, say you sow 100 seeds, using a "normal" hybrid maybe 70 would be the hybrid and the rest would be either on or the other parent type of a weird, unusable mutant (which is, after all, what a hybrid is, a mutant).
Using F1 hybrids pretty much swaps that around, of the 100, 30 might be of the parent type, 70 would be of other types.
F1 hybrid seeds are sold guarenteed to grow as the hybrid, not revert to type.
So either stick your hand in your pocket, grow lots, and throw lots away or just accept that you will get what you get, which might not be what you were aiming for!