Your 6 weeks into flower, most of the strains i've looked into only go for 8 or 9 weeks of flower. The pistols are probably just browning because of time, they're finishing up and just going to be small. There's no reason they won't be good though just because they're small. I don't think this far in there's much you can do to improve the situation other than just improving the lighting and environment.
looks like they had quite a bit of stress in early flower...probably some deficiencies or over watering. Not much you can do this late into flower...just let em finish and try again.