The nail gun: the word "gun" is not a metaphor
A framing nailer drives a three-inch steel fastener with enough energy to bury it in doubled lumber. Nail guns send an estimated 37,000 people to U.S. emergency rooms every year — about a third of them not on the job, but in garages and backyards — and they hospitalize more construction workers than any other tool injury. The gun rules apply because it is one.
Machines and tools vary by brand, model, and age. Your manual outranks this page — read it first.
So borrow the firearms discipline wholesale: never point it at anyone, finger off the trigger until the nose is planted on wood, and treat every gun as loaded — because a nailer with air or a battery is exactly that.
The trigger is the biggest decision
Most nailers offer two firing modes, and the difference is the single largest safety choice you get to make. A full sequential trigger demands a strict order: press the nose against the wood first, then pull the trigger, one deliberate and aimed nail at a time. A contact (bump-fire) trigger fires whenever nose and trigger are both depressed in any order, which lets framers bounce the gun along a deck at speed — and also lets a gun swinging at your side fire the moment its nose bumps your thigh, because your finger was still on the trigger.
Nails don't fly straight through wood
A nail is a projectile negotiating with grain. It follows the path of least resistance — curving along growth rings, glancing off knots, and exiting the side of a stud you were sure it would stay inside. Blow-outs and ricochets are how the holding hand gets nailed, which is why it stays about a foot back from the muzzle, never directly behind the workpiece, and why toenailing — driving at an angle, the grabbiest, most deflection-prone shot there is — earns extra clearance and a planted stance.
Jams, hoses, and ladders
The rest is simpler: never disable or wedge the contact safety tip (it's the only thing making the "gun pointed at your leg" scenario survivable); keep hoses out of walkways and never hoist a connected gun by one; and on ladders, sequential mode only — a bump-trigger gun grazing your leg mid-climb is the textbook incident.
Sequential mode costs a framing crew a little speed on a production deck; it costs a weekend builder nothing at all. Point it only at wood, keep the free hand a foot clear, and unhook the air before touching a jam — those are the habits the injury numbers keep pointing back to, and none of them slow real work down.