I have one of those mini grease guns that takes the small cartridges. I only use it for one thing: marine wheel bearing grease for my boat trailer. I went to use it today and it only lasted a few pumps. I pulled down on the piston lever and a giant glob of grease spewed out the bottom. It turns out the whole cartridge had flowed around the piston and was behind it in the tube. Between the slick hands and general greasiness I managed to dump out and waste most of the grease, which appeared to be about a third of a tube. Is the only fix for this a new grease gun?