I second the Milwaukee M12 battery operated gun. I have nothing but great experience with it. I run a lot of extra thick grease through it and it has primed for the most part with out fail. FYI Milwaukee has a new M18 battery operated gun it looks very similar to the M12. It does have higher pump pressure and a two speeded trigger. One potion for volume and one for pressure. They all come with 5 year warranty. Yes the cost is their for me the time it has save me makes it very worth it. Thanks John