Makes me wonder if the British market is catching up here with composite gaskets. Most seem to work really well, but there are a couple of makers spitting out duds.
If the paper the silicone is bonded to is brittle, they split when you torque them down. I dont know if its one maker, but it always seems the ones that are Red are the ones to watch out for. Maybe its the kind of silicone, maybe its just one maker?