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Quick verdict: which Milwaukee mag drill should you buy?
Choose Milwaukee’s cordless M18 FUEL 2787-20 for work on installed steel, remote jobs, or frequent moves between holes; choose the corded 4272-21 for sustained drilling and cutters up to 2-1/2 inches. The cordless model’s listed maximum cutter capacity is 1-1/2 inches, and its permanent magnet is designed to shut off if the battery is removed or loses power. The corded drill offers greater cutter capacity and a stronger listed magnetic holding force, but it needs a reliable power source and a tether when working overhead.
For a meaningful comparison, focus on the job rather than treating magnet force as a stand-alone safety rating. Surface condition, steel thickness, position, vibration, and the drill’s setup all affect whether a mag drill stays put.
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Milwaukee M18 FUEL vs. corded: the key numbers
The figures below are manufacturer-listed specifications for the Milwaukee 2787-20 and 4272-21. The 2787-20 is the bare tool; battery weight and runtime depend on the M18 battery used. Verify the exact kit and specification sheet before purchase, since included accessories can vary.
| Specification | M18 FUEL 2787-20 | Corded 4272-21 |
|---|---|---|
| Power source | 18V M18 battery | 120V AC cord |
| Maximum annular cutter capacity | 1-1/2 in. (38 mm) | 2-1/2 in. (64 mm) |
| Maximum twist-bit capacity | 1/2 in. (13 mm) | 1-1/8 in. (29 mm) |
| Listed magnetic holding force | About 2,000 lb | About 2,500 lb |
| Weight | About 29 lb bare tool | About 35 lb |
| Automatic magnet shutoff | Yes; designed to release if battery power is removed or lost | Yes; linked to loss of electrical power |
Magnetic holding force is not the same as a safe working load. It is a stated product specification, not a promise that the drill will hold on every surface or orientation. Paint, rust, scale, thin material, curved stock, and gaps beneath the base can all reduce effective grip.
Magnet strength and auto shut-off: what matters on the job
Holding force depends on the steel, not just the brochure number
The corded 4272-21 has the higher listed holding force, which is useful when the tool is properly seated on suitable steel. But a clean, flat, thick surface matters more than a small difference in the headline figure. Before drilling, remove loose scale and debris, check that the base sits flat, and confirm the material is thick and magnetic enough for the machine’s instructions. Do not assume a painted structural member provides the same grip as bare steel.
Both models are substantial tools. Use the supplied safety strap or another manufacturer-approved restraint whenever there is a risk of a fall, especially for vertical or overhead work. Keep hands clear of the cutter and follow the manual’s instructions for positioning and securing the drill.
Auto shut-off is protection, not a substitute for restraint
The M18 FUEL model’s automatic magnet shutoff is particularly relevant when a battery is removed or power is interrupted: the magnet is designed to release rather than remain engaged without the drill’s operating power. The corded model also has automatic shutoff when electrical power is lost. In either case, the feature helps prevent an unexpected magnet state; it does not catch a falling drill or guarantee that the base cannot slip.
That distinction matters on site. If a cord is unplugged, a breaker trips, or a battery is depleted, stop and secure the machine before restoring power. Check the magnet indicator and seating again rather than assuming the drill is still attached as before.
Pick by situation
| Your situation | Better fit | Why |
|---|---|---|
| Drilling on installed steel with no outlet nearby | M18 FUEL 2787-20 | Battery power avoids running an extension cord to the work. |
| Many holes in a shop or fabrication bay | Corded 4272-21 | Continuous power suits longer sessions and avoids battery swaps. |
| Frequent holes larger than 1-1/2 in. | Corded 4272-21 | Its listed annular-cutter capacity reaches 2-1/2 in. |
| Already own compatible M18 batteries and move between locations | M18 FUEL 2787-20 | It can reduce setup time where portability is worth more than maximum capacity. |
| Occasional oversized cuts with dependable power access | Corded 4272-21 | Greater cutter capacity can avoid splitting the job across machines. |
Capacity, runtime, and ownership costs
The 1-1/2-inch versus 2-1/2-inch cutter limit is a practical dividing line. If your work regularly exceeds the cordless model’s capacity, the larger corded drill is the direct choice. If most holes are smaller, the cordless tool may save more time by eliminating cord routing and setup. Do not use a cutter larger than the machine’s rated capacity, and match cutter, arbor, and pilot pin to the drill’s instructions.
There is no useful single runtime figure for the cordless drill without naming the battery, cutter diameter, material, and duty cycle. Larger cutters and tougher steel draw more power; cold batteries and repeated heavy cuts can also reduce useful runtime. For a day of production, plan around spare charged batteries and the actual work rather than assuming a published runtime will hold for every hole.
Compare total ownership cost, not just bare-tool prices. The cordless option may require a compatible battery and charger if you do not already own them. The corded drill avoids battery purchases but may require suitable extension cords and access to the right circuit. Both need cutters and cutting lubricant, and annular cutters are consumables: dull teeth increase heat, slow the cut, and place more load on the machine.
Setup habits that protect the drill and the cut
- Check the base before energizing the magnet: clean the contact area and remove chips that could create a gap.
- Secure the drill: attach the safety strap as directed, particularly on vertical or overhead work.
- Use the right cutter and lubricant: follow the cutter and drill manuals; avoid forcing a dull cutter through the material.
- Clear chips safely: switch off and wait for moving parts to stop before removing swarf. Use a brush or suitable tool, not bare fingers.
- Inspect after use: clean the magnet face, cutter arbor, and vents. Metal chips on the base can compromise the next setup, while clogged vents can contribute to overheating.
In day-to-day ownership, cutters and pilot pins are more routine wear items than the drill body. Repeatedly feeding too hard, drilling without appropriate lubrication, or storing the tool with chips stuck to the magnetic base can shorten cutter life and make setup less dependable.
Bottom line
The Milwaukee M18 FUEL 2787-20 is the more convenient mag drill when portability, access, and quick setup outweigh maximum hole size. The corded 4272-21 is the better production choice when you have reliable power and need its larger 2-1/2-inch cutter capacity or higher listed magnetic holding force. For either model, treat auto shut-off as a useful safeguard—not a replacement for a clean contact surface, correct setup, and a safety restraint.