I'm thinking the grey stuff is very, very, fine sand that will replace the crushed glass. I bought a couple of those kits before I knew how easy it is to get the H48 components I'm still using my first one yet and I make percussion caps as well with my tap o cap!
Traffer, I also used the roll caps and I had a lot of problems setting the mix off by accident. So, I found the recipe and started the H48 mix and I will not look back. Honestly, it is much, much, easier and cheaper, too. I bought all of the components from one distributor. If you want, PM me and I'll fill ya in.
I made a little scooper out of a small pistol primer that I soldered on a piece of stiff wire that gives the perfect amount for a primer, 22 LR, or a percussion cap.
Traffer, you are one of the handiest guys I see posting on this 22 reloading subject, so I would really hate to see you stop posting. Hell, most guys think we're fools for doing it, anyway, so it would bite to loose the input of one of us who are messing with it!