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Why Plumbing Cutouts Are Different
Cutting studs for rough-in or notching out old copper between 16-inch on-center joists is not the same job as demolition. You are working overhead, one-handed, often with the saw body wedged against a joist, subfloor, or drain line. You need to plunge, cut on an angle, and stop before you hit something you shouldn’t. Full-size reciprocating saws are too long and too violent for this. That is why most plumbers doing remodel work have moved to one-handed compact recip saws — specifically the Milwaukee M12 Hackzall and the DeWalt Atomic Compact series.
Both are designed for the same niche: tight-bay cuts where a standard Sawzall or DCS380-style recip won’t fit, and where an oscillating tool is too slow. But they take very different approaches to power, ergonomics, and blade control.
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Size and Access in Tight Joists
This is the single most important factor for plumbing cutouts, and it is where the two saws diverge.
The Milwaukee M12 Hackzall (2420-20 / 2527-20 for the newer brushless Fuel version) is built like a stretched pistol-grip saw with the handle behind the motor. Overall length is about 11 to 11.25 inches with no blade. Weight without battery is 2.6 lbs for the Fuel model. The low profile lets you slide it flat between joists and keep the blade parallel to the subfloor when cutting out a 2×8 for a tub drain or trimming a joist for a toilet flange extension.
The DeWalt Atomic Compact Reciprocating Saw (DCS369) is shorter overall — about 10.2 inches — but taller at the head. It uses the classic inline reciprocating saw layout with the battery at the rear. Weight without battery is about 3.1 lbs, and with a 2.0Ah 20V battery it comes in around 3.9 lbs. In open bays it feels more balanced, but between doubled joists or next to a cast iron stack, that extra head height can prevent you from rolling the shoe flat.
If you routinely work in 14.5-inch bays with PEX, ABS, and blocking in the way, the Hackzall’s slimmer nose matters. If you work mostly from below with decent clearance, the DeWalt’s shorter length makes one-handed overhead cuts less fatiguing.
Power, Stroke, and Real Cut Speed
On paper, the DeWalt wins. On the job, it depends on what you are cutting.
The M12 Fuel Hackzall has a 5/8-inch (15.8mm) stroke and 0-3,000 SPM. The 12V motor is surprisingly torquey but it is still a 12V system. In 3/4-inch plywood subfloor, 1-1/2-inch ABS, and 3/4-inch copper, it cuts as fast as you need. In a doubled 2×10 joist, old nail-embedded lumber, or 2-inch schedule 40 PVC with a dull blade, it bogs down and you will feel the motor cycle and slow.
The DeWalt Atomic has a 5/8-inch stroke as well but runs 0-2,800 SPM on 20V with noticeably more sustained power. With a sharp 6 TPI wood blade or 14 TPI bi-metal blade, it will push through a 2x joist about 20-30% faster and it maintains speed under load better. That matters when you have six cutouts to make for a re-route and you don’t want to change batteries mid-bay.
Trade-off: That extra power comes with more kick. The DeWalt will jump harder if the blade pinches in a closing kerf — common when cutting a joist notch that is under load. The M12 is easier to feather and control for shallow plunge cuts where you do not want to over-cut and hit a wire or supply line on the other side.
Neither saw is meant for continuous demolition. Both will thermally shut down if you try to use them like a full-size Sawzall on a bathroom gut. For plumbing cutouts — short 6 to 12-inch cuts — runtime is not an issue. A single M12 3.0Ah or DeWalt 2.0Ah battery will last a full day of cutouts.
Vibration, Control, and Blade Stability
Both saws use a keyless blade clamp that accepts standard 1/2-inch shank recip blades, but the clamps behave differently. The Milwaukee clamp on the Fuel model is more positive and resists blade wobble, especially with thinner 4-inch and 6-inch blades used for tight cutouts. The DeWalt Atomic clamp is tool-free and fast, but it has a bit more play when you side-load the blade — which you inevitably do when cutting tight against a joist face.
Vibration is lower on the Milwaukee due to lower reciprocating mass and a better counterbalance. Overhead, that means less hand numbness and more precise line following. The DeWalt transmits more buzz into the handle, particularly above 2,000 SPM. It is not severe, but after a dozen overhead cuts you will notice it.
Shoe design also matters. The Hackzall has a pivoting shoe that you can jam against the joist as a fulcrum for a controlled plunge. The DeWalt shoe pivots as well but is wider. In practice, the Milwaukee shoe lets you get closer to a corner where a joist meets blocking or a top plate.
Battery Platform, Weight, and Cost
This is often the deciding factor. If you are already on Milwaukee M12, the Hackzall is a cheap add-on. Tool-only pricing is typically $149-$179 for the brushed version and $169-$199 for the Fuel brushless. It shares batteries with the M12 installation tools plumbers already carry — the Copper Tubing Cutter, the ProPEX expander, and the inspection light.
If you are on DeWalt 20V Max, the Atomic makes more sense. Tool-only is usually $159-$179, but you need 20V batteries which add weight. The Atomic will also run on your existing 20V 4.0Ah and 5.0Ah packs, though they make the saw rear-heavy for overhead work. Most users pair it with a compact 2.0Ah for cutouts and keep the larger packs for drills.
Weight with battery ready to cut: Hackzall Fuel with M12 3.0Ah is about 3.4 lbs. DeWalt Atomic with 20V 2.0Ah is about 3.9 lbs. Half a pound does not sound like much until you are holding the saw above your head with one hand while holding a stud with the other.
Head-to-Head Specs
| Feature | Milwaukee M12 Fuel Hackzall | DeWalt Atomic Compact (DCS369) |
|---|---|---|
| Voltage / Platform | 12V M12 | 20V Max / 18V |
| Stroke Length | 5/8 in (15.8 mm) | 5/8 in (15.8 mm) |
| No-Load SPM | 0-3,000 | 0-2,800 |
| Tool Length | 11.0 – 11.25 in | 10.2 in |
| Tool Weight (bare) | 2.6 lbs | 3.1 lbs |
| Weight Ready to Cut | ~3.4 lbs with 3.0Ah | ~3.9 lbs with 2.0Ah |
| Best For | Tightest bays, control, overhead finesse | Speed, hardwood joists, longer cuts |
| Failure Mode | Bogs in dense doubled lumber, thermal cutout on long rips | Harder kick on pinch, more vibration, bulkier head |
Which to Buy for Plumbing Work
Choose the Milwaukee M12 Hackzall if your work is mostly remodel cutouts in existing joist bays — notching for drains, trimming subfloor around a flange, cutting out old copper or galvanized in a wall where you cannot swing a full-size saw. The lighter weight, slimmer head, and smoother low-speed control make it safer when you are cutting blind next to wiring and PEX. It is also the obvious pick if you already own M12 batteries. The cheaper option is fine here; you do not need 20V power for 3/4-inch pipe and plywood.
Choose the DeWalt Atomic Compact Reciprocating Saw if you cut a lot of old-growth joists, LVLs, or nail-laden double headers and you value speed over finesse. It cuts faster under load and stalls less, which saves time on bigger re-routes. It is also tougher if the saw will do double duty for light demo. Just pair it with a compact battery to keep overhead weight down.
For both saws, blade choice matters more than the saw itself. Use a short 4-inch 18 TPI bi-metal blade for metal pipe close to wood, a 6-inch 14 TPI for ABS/PVC, and a 6-inch 6 TPI wood blade for joists. A pack of compact reciprocating saw blades for tight spaces with those three profiles will cover 95 percent of plumbing cutouts. Change blades often — a dull blade is what causes pinches, smoking, and broken joist fibers, not the saw.
If you do not already live on either platform and you only need a saw for occasional plumbing cutouts, buy on weight and handle preference. Hold both if you can. The saw that lets you keep the shoe planted and the blade straight in a 14.5-inch bay is the one you will make cleaner, safer cuts with.