I gave my SRT7 to my brother, and then ordered a new one to replace it. The first one (black), was super smooth. The second one (grey), is stiff and gritty feeling. Not pleasent to use. I have dribbled silicone grease and dry film lube into it, but it still feels bad. I noticed that if I pull the ring down, toward the battery tube as I turn it, it rotates more smoothly. If anyone knows how to disassemble, I would like to give it a shot.
I miss my old black SRT7. It was my first nice flashlight. I bought it at REI.