Weight: 8.6 pounds
Size: 14 1/4" H x 21 1/4" L
Nail length: 2" to 3 1/2"
Nail diameter: .113" to .148"
Capacity: 65 nails
Street price: $260
The D51850 has a nice set of features: toolless depth-of-drive, a top-loading magazine, a rafter hook, and an anti-dry-firing mechanism.
On most guns the depth-of-drive mechanism is controlled by a thumb-wheel, but on the DeWalt it's controlled by a spring-loaded button on the nosepiece. The button "unlocks" the nose so that the operator can easily set the depth by extending or retracting the contact element. Unlike a thumb-wheel, the button won't strip out or become jammed with grit.
The aluminum magazine loads from the top, making it easy to swap out fasteners. Some top-loading magazines loosen over time, allowing the nails to flop around and jam; but the magazine on the DeWalt is very solid, and we haven't had any jamming problems.
The D51850's depth-of-drive mechanism is quick and reliable: You press the unlock button, slide the contact element in or out, then hit the lock button.
The tool's plastic rafter hook pivots to both sides of the grip or completely out of the way. I'm a big fan of rafter hooks, so I really appreciate this feature.
The DeWalt Web site makes much of the gun's anti-dry-firing mechanism, which reduces wear and prevents the carpenter from nailing with an empty tool. But in fact the feature is not unique; many framing guns now have it. The mechanism on the D51850 prevents the gun from firing when you're down to seven nails, which we found irritating; with certain brands of fasteners we couldn't reload two full strips.
The gun is well-balanced, has a comfortable grip, and feels solidly made. It has very good power and had no trouble driving 3 1/2-inch by .148-inch fasteners into solid lumber.
It came with a sequential trigger that we immediately swapped out for a contact trigger. A video on the DeWalt Web site shows the gun bounce-firing into LVL material. We tried this on site and the nails stood proud — even with the compressor set to 120 psi. Fortunately, bounce-firing into LVL beams is rarely necessary — and we found that if we slowed down a bit, the gun was able to fully set fasteners in the material.
DeWalt's rafter hook — shown here in the center position — pivots left, right, or out of the way.
Size and weight. According to DeWalt, the D51850 weighs 8.2 pounds — about average for a framing gun. But this spec is incorrect. When we put an air fitting in the tool and weighed it empty, we got 8.6 pounds — which is heavier than the average framer.
There are some benefits to a heavier gun. The two 7.6-pound DeWalt D51845s we own do a poor job absorbing recoil; that's not an issue with this new model. Also, the D51845s aren't especially durable — we've had trouble with the quick-release magazine. It's my sense that this heavier tool will hold up better than those earlier models.
Weight: 7.5 pounds
Size: 11 5/8" H x 20 5/16" L
Nail length: 2" to 3 1/4"
Nail diameter: .113" to .148"
Capacity: 60 nails
Street price: $285
The SN902XP was designed to compete with small lightweight nailers like Hitachi's NR90AE and Max's SN883RH. It weighs 7.5 pounds with an air fitting and is only 11 5/8 inches high — short enough to work in narrow rafter bays.
The Senco nailer has most of the features found on the DeWalt — though not a rafter hook. This is a serious oversight: It makes working up high inconvenient and increases the likelihood that the tool will fall and break.
On the Senco nailer, depth-of-drive is controlled by a large metal thumb-wheel tucked well into the nose of the gun.
I like the SN902XP's depth-of-drive mechanism. The thumb-wheel is large and easy to use, and since it's made from metal (rather than plastic), it's unlikely to strip out.
Selectable modes. With some guns you have to choose between a sequential and a contact-trip trigger, but the Senco has a built-in switch that allows you to go back and forth. We set it to contact unless we have to nail close to where we grip the material; then we switch to sequential.
The gun also has what Senco calls a True Drive magazine, which is supposed to reduce jamming and misfeeding. However, we experienced a fair amount of jamming because nails wouldn't stay in line; also, the plastic pull sometimes bound in the magazine.
A trigger on the SN902XP allows carpenters to switch back and forth between sequential and contact trip, enhancing safety.
A few days after we began using the gun, the piston got stuck in the up position. This had never happened to me before. To fix it, we removed the end cap, pushed the piston down, poured in some gun oil, pulled the piston back up, and reinstalled the cap. The problem has not recurred. I suspect it was due to a lack of oil in a very new gun.
The Bottom Line
As a framer, I found the DeWalt to be a solid performer. Although heavier than average, it's comfortable to use. It has plenty of power and seems rugged enough to stand up to the kind of abuse tools get on framing sites.
If I were a remodeler I'd be tempted by the Senco's light weight and compact size. But I didn't like the magazine, and I have enough concerns about the tool's durability that I wouldn't recommend buying it.
Tim Uhler is a lead framer for Pioneer Builders in Port Orchard, Wash., and a JLC contributing editor.