How to Use a Trim Nailer Gun

Updated: Oct. 10, 2018

Avoid common mistakes with a pneumatic nail gun.

finish nail gunFamily Handyman
Learn to use a trim gun and you'll never want to pound another finish nail. A trim nailer will give you superior results with less effort

You might also like: TBD

An hour or less

Learn to use a trim nailer

The first time I used a pneumatic trim gun, I was hooked. It’s not just that it was lightning fast. I loved being able to install hardwood moldings without predrilling to prevent splitting, and I was happy to leave my nail set mostly in my toolbox. But even better was the fact that nail guns allow you to hold a molding in exactly the right spot with one hand while you instantly nail it in place with the other. And small nail guns called brad nailers allow you to quickly and easily secure thin, fragile moldings without ruining them. That’s a job that otherwise requires the dexterity of a surgeon.

But things can go wrong. In this article, we’ll show you the most common problems you’ll encounter when nailing trim with a finishing nail gun and the techniques you can use to prevent them.

Avoid blowouts by watching the angle

Photo 1: Problem: Nail blowout

If you’re not careful the nail will come out where you don’t want it.

PHOTO 2: Solution: Angle the gun in

Angle the gun toward the unseen side.

Once you master this angle technique, you’ll have no trouble shooting nails exactly where you want them. Start by positioning the center of the finish nail gun tip exactly where you want the nail to enter the wood. Then carefully align the nail gun with the path you want the nail to take, just like when you line up a pool cue before striking the ball. Photo 1 shows what can happen if you get careless and angle the gun wrong. When you’re nailing into door jambs or other areas where only one side shows, point the finishing nail gun slightly to the hidden side where it won’t show if the nail pops through (Photo 2).

Occasionally nails hit a knot or follow the grain—and pop out despite your best effort. If this happens, break or cut off the protruding nail with a nipper and use your nail set to recess the remainder.

Avoid split ends by placing nails accurately

Photo 3: Problem: Split trim at the ends

Be careful. If you nail too close to the end of the trim, it’ll split.

Driving nails with these finishing nail gun tools is so simple that it’s easy to get carried away and put nails where they don’t belong. (Ask any painter who has to putty all the extra holes!) With practice, you’ll get a feel for where the nail comes out of the finish nail gun and be able to drive a nail precisely. Photo 3 shows the result of placing a nail too close to the end of a molding. The same thing will happen if you nail too close to the end of a baseboard, especially on short pieces. Make sure to keep nails a few inches from the end of moldings to avoid splitting the wood. Brad nailers, which drive thinner and shorter nails, are the exception. With these, you can usually nail within 1/2 in. of ends and 1/8 in. of edges without splitting the wood.

Use the right size nail

Photo 4: Problem: Exposed nail

If the nail is too large it can come out where you don’t want it.

Photo 5: Solution: Use a smaller nail

Brad nailers are better for work that’s close to edges

Different nail sizes

Be sure to get the right size nails for the job.

Changing nail sizes in the middle of a job is bothersome. It’s tempting to use the nails that are loaded and hope for the best. But it’s a bad idea.(Photo 4). We should have used a 3/4-in. brad or at most a 1-in. 16-gauge nail on this miter. A good rule of thumb is to pick a nail long enough to go through the material you’re fastening and penetrate the underlying wood about 3/4 in. to 1 in. Allow more penetration for heavy-duty jobs like nailing door jambs, and less for fine work like securing miters.

I own a 15-gauge nailer and a brad nailer and keep them both connected to separate hoses while I work. (Install a T-fitting at the compressor to connect two hoses at once.) With this setup, it’s an easy matter to pick up the brad nailer for intricate jobs like pinning.

Buying or Renting Nail Guns

If you can afford it, buy both a 15-gauge finish nailer and an 18-gauge brad nailer. The two guns make a winning combination. The 15-gauge nails, ranging in length from about 1-1/4 in. to 2-1/2 in., are strong enough to secure door jambs and other heavy trim materials. Plus, the angled nose on most 15-gauge nailers allows you to nail in corners and drive toenails more easily. Prices for 15-gauge nailers range from $230 to $350.

Fifteen-gauge nails are too thick for many fine nailing tasks. And this is where the 18-gauge brad nailer excels. They shoot very skinny 5/8-in. to 1-1/2 in. long, 18-gauge brads. These are perfect for nailing miters (Photo 2), nailing the skinny section of door or window casing to the jamb (Photo 3) and other nailing jobs where a larger nail would split the wood or protrude through the other side of the material. Prices range from $70 to $200.

Having both guns connected to your compressor with separate hoses means you can nail the inside and outside edge of casings without having to change nails. And you’ll always have just the right size nail for the job at hand.

If you don’t do enough trim work to justify the expense of two nailers, a 16-gauge nail gun is a good choice. The 16-gauge nails are a bit skinnier and not quite as strong as 15-gauge nails. But they’re less likely to split thin pieces of wood. Most 16-gauge nail guns will shoot nails ranging from 1 in. to 2-1/4 in. Prices range from $200 to $300.

Avoid underdriven nails

Photo 6: Problem: Nail won’t set flush

Nails that don’t set must be driven in or removed. Use side-cutting pliers to pull protruding nails. Or use a nailset and hammer to drive them in.

Photo 7: Solution: Increase the air pressure

Increase the air pressure on your compressor, or use a smaller nail if the nails aren’t being driven in completely.

Nails that don’t set, or that are left sticking out (Photo 6), are usually the result of pressure that’s too low, a nail that’s too long or an improperly adjusted nail gun. If the nail is sticking way out like the one in Photo 6 try increasing the air pressure to the maximum allowable for your finish nail gun (90 to 100 lbs., or check your instructions). If the nail still won’t set, try loading shorter nails or brads.

The nosepiece on some finish nail guns is adjustable to help control how deep the nail is set. Use this in conjunction with pressure adjustments (Photo 7) to fine-tune your finish nail gun until the head of the nail or brad is slightly recessed. Keep a nail set handy for the occasional protruding nailhead.

Don’t bother pounding in nails that protrude more than 1/4 in. They’ll just bend over and dent the trim. Instead, grab the shank and bend it back and forth until it snaps, or use a side cutting pliers (Photo 6) to cut the nail near the surface. Then recess the rest with a nail set.

Finish Nail Gun Safety

Pneumatic nailers are unbelievably fast and powerful. One careless second is all it takes to lose an eye or put a nail through your finger. Here are safety precautions you should take with a finish nail gun:

  • Disconnect the air hose from the gun when you’re loading nails or clearing a jam, or when you’re not using the nail gun.
  • Wear safety glasses and have your helpers and bystanders wear them too.
  • Keep children away from nail guns. Disconnect the gun and put it out of reach when you’re not using it.
  • Keep your fingers well away from the nail’s path. Use clamps if necessary.
  • Never rest the gun on top of a ladder.
  • Keep your finger off the trigger when you’re not firing the gun.

Other problems you might encounter

Finish nail guns can be a little finicky. Here are a few common problems and possible solutions:

  • If the finish nail gun fires but no nail comes out even though you can see nails in the clip, the nail feed mechanism may be sticking or the nails may be binding in the magazine. Remove the nails and lubricate the magazine and spring feed with spray silicone.
  • If the finish nail gun doesn’t fire even though it’s loaded with nails (you won’t hear or feel the piston and driver move), it’s probably not getting enough air. Make sure the compressor is plugged in and that the fuse or circuit breaker isn’t tripped. Then check the gauge to be sure the pressure on both gauges is set high enough.
  • If a nail jams in the nose, disconnect the hose from the gun before you do anything else. Remove the nails from the gun. Then open the nose (check your instruction manual if you’re not sure how) and remove the jammed nail.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Air compressor
  • Brad nail gun
  • Hammer
  • Hearing protection
  • Nail set
  • Nippers
  • Safety glasses

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Trim gun nails