I've always used to load my grease gun manually from a tub. The thing however makes a mess everywhere. Does this also happen when you use cartridges in them? I have not used them before.
I've got 2 that leak with grease tube cartridges and one old one that doesn't and its pretty old. I think its a quality issue. I've noticed that synthetic lube seems to leak more than all-purpose lithium in mine. Maybe it just seems like it because it costs more.
All of my grease guns leak. They vary in vintage from the late 1980s through the early 2000s. They're all typical low-priced auto parts store gease guns. In the end, they get the job done and I suppose that's what matters.
I was told I was using the wrong kind of grease, and will switch as soon as I use what hasn't leaked out! Now if I could only remember what kind they told me to use......LOL.
I've had and have regular-sized grease guns, those small one-handed jobs, and even a pneumatic one. All of them have leaked and had other issues. Some were cheap, some pricey. They all have issues.
All my grease guns leak, even the most expensive Lincoln and Alemite ones. I think the grease just oozes past the seals over time. A cartridge gun has no seal between the head and the barrel - it relies on the metal head bearing against the metal lip of the cartridge. The rubber cup on the spring-loaded follower of a cartridge grease gun isn't a true "seal" since it has no real sealing lip. I think that comes from having to slip into the cardboard tube of the cartridge. A real seal would catch on the mouth of the cardboard tube and damage it. I think that the shaft on the follower doesn't seal well either. This is related to it's need to rotate in relation to the head and end cap in order to lock open.
I wonder if the follower would leak less if you kept it locked open when not in use?