Hitachi NV50AP3 1-1/4-Inch to 2-Inch Cap Nailer Brand new gun, just bought it. Gun does not always cycle properly or cleanly cut the plastic caps off of the roll. Many times the cap just nailed is still attached to the roll, you have to twist the cap off and then re-set the roll to start again.

You can use most gases in your gun, but paslode is the best that's why its more expensive. Try warming the gases in your pocket that sometimes helps.

did you look for a clog in the air passage inside the gun when you took it apart?

This is a bottom fire tool. (NV83A2) You need to hold the trigger down and then as you place the nailer to the wood the safety will depress and it will fire once. This is usually done in one, swift action. If you do this in the opposite way by placing the tool to the wood and then pulling the trigger they often will double fire.

New user will jam the gun/ nails because gun was most likely not bump fired. Placing the gun then depressing trigger will usually cause double fire in the hands of new user. New user should practice on scrap lumber bump firing at many angles till they get the idea; or give them a training period with a nailer that has a single shot trigger (they may develop bad habits with single shot however).

Over time debris enters the gun and scratches the metal and plastic surfaces where orings seal against. These scratches will allow air to leak past. Remove the head and pull out the head valve. Examine the metal surface with magnify glass where the headvalve oring makes contact. Remove scratches with 400 grit paper. The surface must be smooth and the oring must seal snugly. Apply silicone paste lube on all surfaces and orings (available at Lowes in the plumbing department and swimming pool supply). Also check for scratches around the body of the gun were the cylinder plate is installed around the cylinder. The gun will not work properly will small air leaks. Remove nails and listen for leaks thru the nose of the gun. Repair as needed. Good luck with your gun.

Water in gun or wrong oil for cold temp will cause gun to freeze. Make sure that the compressor is not making water form in hoses due to hot air entering cold hose then freezing in gun. Remove cap of nailer and check for water and lube with light oil that remains liquid in your temp range. If the oil is too thick, the firing valve under trigger and headvalve will not budge. Use very short hose so warm air in tank can reach the nailer (heat is produced when air is compressed, however long hose will allow air to cool before entering gun). Stay warm and good holidays

If the gun is blowing air out the back cap it needs an overhaul. If you take it to a service center they will be able to supply you with the proper O-Rings or if you pay a little more they will overhaul it for you.

This probably is the problem,

The cylinder that the piston moves up and down inside is probably to low, and not making contact with the rubber piece in the head cap.

The cylinder has a spring that allows for movement up and down, take a pliers and gently pull up the cylinder if it does not move freely on its own. It will stop when it reaches the cylinder plate ( the part with 2 screw holes for easy removal). Be careful not to mar the cylinder though.

When reassembling the cylinder should make contact with the head cap. Hope that works!

If you do not have a breakdown of the gun go here www.toolpartsdirect.com and select brand, then select coil nailer, finally look for your model number. With breakdown, find parts labeled 51 thru 54. The trigger pin (#53) and the retaining ring (#21) hold the trigger. Remove these then remove the trigger. Find several #51 roll pins on the gun and punch out the uppermost pin where the trigger valve is located (3mm size). The uppermost rollpin holds the trigger valve in-place. After you have removed the rollpin/s connect air supply to pop-out the trigger valve. Caution, use a heavy glove (or reduce pressure) to catch valve as it can come out with force. When incerting the rebuilt valve, use caution not to cut new orings as the valve is pushed in. Good luck and email if you have more questions.