Coupler Warning
I bought an 1134 from Amazon and it is not Made In USA. On to the coupler... there is nothing in the user manual about how it works. And good luck getting any help from Lincoln!

The coupler knurled section is tightened for shipping and you need to break it loose before you use it. It will go on and pull off the zerk until you pump grease and then it will not let go until you back off the knurled section. Don't try it on a zerk that is in a pocket that prevents you from getting your fingers on the knurled section or you may never get it off the zerk. When you have the coupler on a zerk as you rotate the knurled section you can feel the change in how it grips the zerk from locked on to loose and removable.

This feature? may be nice because you don't have to hold it on to the zerk and it will allow very high pressure. But if you need to use it in an area like a U-joint with a zerk that is deep in the spider, and you can't get to the knurled section of the coupler, you have to find a setting that will allow you to pull the coupler off and still seal to the zerk enough to push grease in and not just splooge all over. Pushing the coupler against the zerk while you pump does not seal at all.

Also, if you don't uncock the cartridge spring it pushes the oil portion of the grease out the nifty Lincoln Grease Gun Filler Pump Nipple on the head.

Amazing
Works great on ford trucks. Doesn't latch on too tight, must have fixed it.

problematic coupler
I recently purchased a Lincoln 1134 grease gun. Its well constructed and the level delivers more than adequate pressure. BUT the coupler is nothing but problems. It fits on a grease fitting easily, but will not come off. I have to unscrew the tip to remove it. Not only is this a major pain, but it also causes the grease fittings to loosen.

There is another Amazon review that talks about problems removing the coupler - but it gives the problem 5 stars. If you have to wrestle with the gun with each grease fitting, its not very useful.

One more thing - the instructions are really lame. I took apart the coupler, hoping to find some problem and referred to the parts diagram to reassemble. Low and behold - the coupler parts are not shown in the diagram.

I've registered a complaint on Linclon's website, but have yet to hear from them.

Handy tool but coupler too tight
The one hand pump is a great improvement in my tool kit. Made of good materials. Only problem, as others have mentioned, is the coupler is too
tight. When removing the grease gun I pulled the zert out of the mower wheel. Maybe the company will send out a redesigned coupler to its recent customers in the interest of happy campers and more referrals to their productLincoln Industrial 1134 16 Ounce Pistol Grease Gun with 18" Whip Hose and 6" Rigid Pipe? Just a fraction larger and it would be a perfect tool. TBS

Linhcoln 1134 grease gun
Superb tool, easy to use with enormous pressure with one hand operation. The very best price on the internet especially with free shipping. I always look at Amazon first when I am looking