That white stone is called Chert. the distinction between "flint" and "chert" is often one of quality - chert being lower quality than flint. Flint is a member ofthe Chert family. Chert will spark well, but it breaks down faster then a good english flint. A lot of people shoot with Chert. And they call it Flint which as far as I am concerned is fine. But flints come in black (english), brown (germany), and (French) amber. Chert can be anything from white to black with a mix of colors in there... even green.

That is some good shooting there with the FFFg. All of them loads are deer killers with that kind of group. I wonder if your one squib load might have got an over saturated olive oil patch and you loaded hard, pushed oil out alone the touch hole, and it contaminated the load.

What I find most intesting is the velocity of the loads. I like to compare the loads you shoot and the loads Big6x6 shoots because he shoots Swiss. There is quite a difference.