For both consumers and workers, nail guns make fastening tasks remarkably efficient. But along with ease of use and productivity, nailers also bring considerable health risks, risks which are sometimes inherent to the product itself. Researchers at Duke University and the Centers for Disease Control found that nail gun injuries had more than tripled between 1991 and 2005. And from that year to today, little has been done to curb the availability of nail guns or regulate their more dangerous aspects.

One important safety measure has been instituted, but it’s far from becoming an industry-wide precaution. You’ve probably seen it around the workshop, on the job site, or in your own hand. If your trigger is black, you’re using a contact trip mechanism. If it’s silver or gray, you’re using the sequential trip. But what does that difference mean?

Contact vs. Sequential Trip Nail Gun Triggers: Uses & Safety

Contact trip triggers are by far the industry standard. Contractors generally purchase contact trip nail guns for one simple reason: they’re faster. Faster tools make for more efficient workers and employees who spend fewer, more productive hours on the job equal less-expensive construction projects in the long run.

Contact trip nailers only fire when both their manual trigger and their trip, the gun’s nose, are depressed simultaneously. That’s true for sequential triggers, too, but a slight difference between the systems has a huge impact on both the tool’s use and its relative safety.

Why Are Contact Trip Triggers So Popular Among Workers?

Both types have two triggers: the manual trigger and the nose trip. But for contact trip nail guns, the order in which you pull triggers doesn’t matter. The gun will drive a nail when you press the trip down first, or if you pull the manual trigger first.

Many contractors, framers, and roofers prefer this method because it allows for “bumping” or “bump nailing.” Hold down the trigger and bump the trip across a workpiece, and the tool will drive a series of nails continuously. Contractors argue that “bump nailing” can speed up projects considerably, keeping costs low and profits high.

You can also “place nail” with a contact trip trigger nail gun. Depress the tip against a work surface first, then pull the manual trigger, and the nailer fires. Place nailing tends to create a lot of recoil, and the tool can bounce off the material being fastened. Of course, many workers are aware of this, and actively “fight” the recoil. If the tip makes new contact with the work surface, a second, unintended nail may be fired. If the tool makes incomplete contact with the surface, or twists at an angle, it can even fire nails off into space, endangering other workers. This is a common cause of nail gun accidents. To learn more, visit our “Nail Gun Accidents” page.

Neither bump nailing nor place nailing are ideal where safety is concerned. Sequential trip triggers largely solve the problem.

Are Sequential Trip Triggers Safer?

Sequential trip requires that both triggers be actuated in a specific order. The gun will only fire when the contact, the tool’s nose, is depressed before its manual trigger is pulled. This eliminates the possibility of bump nailing, but also of accidentally driving a nail when the contact tip remains depressed.

In 2003, the American National Standards Insitute, a private non-profit that brokers voluntary standards within multiple industries, called for all large pneumatic framing nailers to be shipped with sequential triggers. But this standard isn’t legally binding in any way; it simply represents a general understanding that people should be using sequential.

Another problem? The standard doesn’t require manufacturers to ship FULL sequential trips, just sequential trips. While safer than contact triggers, sequential are still not the safest option.

What Is A Full Sequential Trip Trigger?

There are two kinds of sequential triggers used within the industry today: single and full. The difference comes after you’ve driven one nail, and want to fire another. With a full sequential trigger, you would have to release each trigger, both the contact tip and the manual, before refiring. With a single sequential, you only have to release the manual trigger. Keep the tip depressed, squeeze the trigger again, and the nail gun will drive another nail. This allows workers to fire multiple nails in one go but increases the risk of accidents. For one, the second nail may accidentally ricochet off the first, firing into surrounding space and harming the operator or another worker.

Regulatory agencies, including the Occupational Safety & Health Administration, are unequivocal: full sequential triggers are the safest option. Some nailers come with a switch, that automatically converts a trigger from contact trip to sequential mode. But although many pneumatic nail guns now ship with sequential triggers installed, electric nailers usually don’t. You may have to search out a sequential trigger and install it yourself.

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