Milwaukee M12 Cordless Grease Gun Review: Best Battery-Powered Gun for Field Use
Last updated: 2026-09-04 · By NicheHive Editorial
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Milwaukee M12 2446-20 cordless grease gun reviewed for pressure, shot counter accuracy, battery life per cartridge, and how it compares to manual lever guns and Lincoln Industrial for shop and field greasing.
Milwaukee M12 Cordless Grease Gun
Milwaukee
Milwaukee M12 2446-20 is the best cordless grease gun for anyone who greases equipment regularly — the shot counter and variable speed eliminate the two most common manual greasing mistakes (under- and over-greasing). For users already in the M12 ecosystem: this is the obvious choice. For occasional home use: manual guns are less expensive and require no battery maintenance.
Pros
- 8,000 PSI — sufficient for nearly all automotive and agricultural zerks without manual effort
- Built-in shot counter tracks grease output per fitting for accurate greasing
- Variable speed trigger allows slow, precise delivery for small fittings
- M12 battery platform — shares batteries with 200+ Milwaukee tools
- LED work light illuminates dark fitting locations under frames and panels
Cons
- M12 battery not included in bare-tool version — requires existing M12 platform or additional purchase
- 8,000 PSI is below the Lincoln 1134's 10,000 PSI — does not clear the most severely packed zerks
- Motor is audible during operation — some users find it disruptive in quiet environments
- Cold weather reduces battery capacity and grease flowability together
The Shot Counter Advantage
The most useful feature on the Milwaukee M12 grease gun is the built-in shot counter — a digital display that counts each shot of grease delivered. This addresses the most common greasing mistake: injecting an unknown amount.
How to use it: reset the counter at zero before greasing a fitting. Inject grease until you reach the target count for that fitting type. Common targets: automotive wheel bearings 3-4 shots, U-joints 1-2 shots, tie rod ends 2-3 shots, ball joints 3-5 shots. Record the count for each fitting on the equipment — this creates a repeatable greasing procedure.
Manual lever guns have no counter. Experienced mechanics estimate by feel. Inexperienced users over-grease, which blows seals, or under-grease, which fails bearings. The shot counter makes precision accessible regardless of experience level.
Pressure and Variable Speed
The M12 delivers 8,000 PSI maximum. This handles standard automotive and agricultural zerks, including moderately packed ones. It does not match the Lincoln 1134's 10,000 PSI for severely packed zerks.
Variable speed trigger control is meaningful for small fittings. At full trigger: 8,000 PSI delivery is fast — for a U-joint that takes 1-2 shots, full speed risks over-delivery in 1-2 seconds. Half trigger: approximately 3,000-4,000 PSI with slower flow — appropriate for small fittings where precise control matters. The Lincoln 1134 lever gun has no variable output — every stroke delivers maximum force.
Battery Life
On a 2.0Ah M12 battery: approximately one full 14oz cartridge of NLGI 2 grease before recharge. On a 4.0Ah: two cartridges. In cold weather (below 5°C): battery capacity drops 20-30%, and grease viscosity increases — expect roughly 30% fewer shots per charge in winter.
If greasing is done infrequently (monthly service on home equipment): battery self-discharge is a consideration — M12 batteries hold charge well for 3-4 months but will need a charge before use after longer storage.
M12 Ecosystem Value
The M12 platform includes over 200 tools — drills, impacts, lights, fans, inflators, and more. If the shop already runs M12, a second or third battery serves the grease gun at no additional cost. For users with no Milwaukee investment: factor in the cost of at least one battery (approximately $40-60 for 2.0Ah) in the total cost.
When to Choose Lincoln 1134 Instead
For manually operated zerks that require maximum pressure (10,000 PSI): the Lincoln 1134 lever gun exceeds the M12's 8,000 PSI and requires no battery. Choose the Milwaukee M12 when:
- Shot counting matters for procedure compliance
- Cordless operation is required
- The M12 platform is already in use
For the full comparison, see Lincoln 1134 vs Milwaukee M12.
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