As I received a couple of tins of GLOP as a free sample from JD Reloading following their introductory post, I thought it fair to write a quick review of it.
GLOP is a lubricant for use in blackpowder firearms and so far it has performed well. It is usable in a range of temperatures, not too hard when cold and so far has done OK when its warmed up a bit too. I have problem with some lubes melting on a warm range day, like butter in the sun, but I don't think this will do in the same way. I coated some lead balls with it and they did aid loading a little and cleaning was certainly easy. In a .36 bp rifle I used it as a patch lube and again it aided loading and the usual sooty residue was easy to clean afterwards. I have used it to seal the chambers on a bp revolver and it covered the chamber fairly well but lacked the bulk of other lubes I've used and wasn't as easy to use, but I guess this may not be its primary role.
I am not someone who makes his own bullet lube and I haven't used many commercially bought ones, but GLOP did what it was supposed to do well and it even smells quite nice. It is very greasy and unless you are careful can leave your hands slippery. I always have a rag to wipe my hands on when blackpowder shooting and I did need it with this. Would I buy it? Yes probably, providing the postage costs weren't prohibitive.