Mastercraft Brad nailer piston always fires damaging finish but nail gets randomly shot. Thought it was a indent before nail shot to indent nail since it mostley shoots nails after second shot but lately missing 4 or 5 times befoe nail shoots. Damages finish alot. Anybody have an idea why? Could it be quality of nails? Also, dial on top of gun back what is that for?

Is there an adjustment setting for different powers? Maybe you need to increase the power that the nail is being put in with.

No experience of Mastercraft brad nailers but if fires with out depressing nose tool is dangerous and should be returned to manufacturer. Dewalt make battery powered brad guns and recently produced a battery framing nailer. I would not say that other nail guns are exactly cheap if they are beware they may not be up to the pressures excerted on the whilst firing.

This happens. The follower jumps over the nails and the magazine binds.

Step 1. Remove nails, unplug hose.
Step 2. Remove the bolt at the bottom of the magazine with a 2.5mm hex key.
Step 3. Remove the magazine while holding the nail follower in place to the magazine cover.
Step 4. Carefully remove the nail follower and gently extend the yellow warning indicator and follower spring.
Step 6. Inspect the nail follower. There should be 3 indentations that are stamped into nail follower face. This is the culprit.
Step 7. With a small punch, make these three indentations deeper.
Step 8. Assemble and test. Repeat if necessary.

Hope this helps.

If a gun is firing and nails are not being driven into the work it's because of one of two problems. The nails aren't feeding fully under the driver or the driver isn't fully retracting each time the gun is activated. Is looks like you've eliminated a feed problem so you are going to have to take the gun apart to find out why air is not being held in the bottom of the head long enough to push the driver back up the cylinder. Go to www.ereplacementparts.com and bring up your model so you can follow along. Remove the four screws holding the head cap on. The things that can cause your problem are: the piston seal & o-rnig are damaged, the cylinder is badly scored, the o-ring & cylinder ring on the bottom half ot the cylinder are damaged or out of place, or the driver guide under the bumper is broke or missing. If it turns out internal parts are damaged or missing, I highly recommend the overhaul kit to replace all the 'soft' parts inside the gun as long as you have it apart.

Remove nails and use thin tool to push driver all the way up to top of cylinder. If the gun fires one nail then skips, the driver is not returning to top of cylinder. If no nails fire, then nails are not feeding into proper position. Driver must return to top to allow nails to feed into position. Most common problems are bent driver, worn piston oring and bad batch of nails(head too large). Good luck

Not sure about Senco but most have latch you can open to expose firing mechanism. Nail sometimes gets jammed and will not allow driver to fire or if not nail push driver ****** all the way back into gun then see if gun will fire.

The dent in the wood is not caused by the air. It's caused by the set that drives the brad. Are you oiling it consistenly? Are the brads the right manufacturer for your porter cable brad nailer? From the information you give it appears that the brads are not advancing correctly or that the air pressure is not sufficient to dislodge the brad from the brad strip on the first strike - it takes an additional strike to break it free. The standard for adding oil is to add ten drops of air tool oil for every hour of operation. That seems like a lot, but the correct amount of oil is a sure way to prevent most air tool problems.

Strip and clean the whole diaphragm and spring arrangement. Also check whether a bad nail hasn't damaged the piston guide and caused it to jam when on return stroke.

First - the air pressure has to be high enough - check the regulator on the tank to make sure it is delivering in excess of 60-70 psi (which I am sure you have already done).

If you have dry fired these guns (i.e. shot them off with no nails in them while you were lubricating them maybe) the mechanism inside could be damaged. I had that happen to one of my nailers (same brand). That was when I learned not to dry fire them...

Since both of them are not working though I would be more inclined to look at the air supply first.

Look for a jam in the gun.Sounds like a brad is "hung up" in it, probably right at point where it feeds into the mouth of the firing point. Be sure you unplug it before you do this.