How Not To Fill Grease Gun

Don't know if the zerk fittings I found on the front suspension of my 1996 Dodge Dakota were factory installed or are the result of aftermarket replacement components. Any way, my Autozone purchased grease gun (pistol grip) never seemed to work right until I watched a video on how to refill it. I was keeping that rod pulled part-way back when I should have pushed it back in all the way once the top was screwed on almost tight. Live and learn.