Milwaukee M12 Gen II 3/8-Inch Stubby Impact Hands-on Review

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I recently tested out Milwaukee’s M12 Gen II Stubby 1/2-inch-drive impact wrench. The size-to-power ratio absolutely blew my mind. It’s extraordinarily powerful for its size, yet small and lightweight enough that you can take it anywhere and use it all day without a hitch. But as good as it already is, Milwaukee might have made it even better.

Milwaukee’s M12 Gen II Stubby impact wrench line, has expanded with the addition of the 3/8-inch drive version. It sent one over for review alongside the 1/2-inch model. While you might be quick to write off the differences, there is a major advantage to the smaller drive. It makes for what I’d consider the perfect impact wrench for a roadside kit or any job that takes you out of the shop.

The only thing that separates Milwaukee’s Gen II Stubby 3/8-inch drive impact is the size of the anvil. That means everything good carries over. Again, that includes the absolutely wild power output despite its compact size.

The M12 Gen II Stubby delivers an astounding 550 foot-pounds of breakaway torque. That’s a lot of snot from a tool that’s smaller than most impact drivers and weighs next to nothing. It comes in at 2.2 pounds without a battery and 2.7 pounds with a 2.5 Ah battery. Installing the 5.0Ah battery brings the total weight to 3.2 pounds.

The 4-mode drive control also carries over. Modes one through three are simply gradual increases of speed and power, with the fourth being the Auto-Shut Off mode. Selecting modes is as done by setting the drive to neutral and pulling the trigger twice. The 3/8-inch Gen II Stubby also shares the same retail price of $199.00 with its 1/2-inch counterpart.

Performance testing of the M12 Gen II 3/8-inch Stubby impact wrench consisted of using it for a variety of jobs around the shop and outside of it. I’ve recently started to tear down the 4.7-liter V8 in my 2003 Ram 1500. This has seen me through a lot of the work alongside the 1/2-inch version. I’ve also tackled a few suspension jobs and, took it along with me for a trip to the junkyard.

In the case of the 3/8-inch drive model, that maximum power is nice to have but isn’t always necessary. You’ll almost never run into a fastener this tool is intended to work with that requires anywhere near 550 foot-pounds of torque. For the most part, I leave it in the second power level mode. This setting is more than capable enough for most fasteners but isn’t so powerful that you have to worry about breaking things. The third mode is mostly there for special occasions.

Still, that compact size pairs nicely with extreme power. When you’re working under a car or in an engine bay, you don’t have a lot of room, if any, to get a bigger impact or breaker bar in there. This has no problem getting in and going to work. A weight of just three pounds is also easily manageable over long periods. And that kind of power means you don’t need to stop and swap tools, even when you have room to. It will be the only impact wrench you need for many jobs, and that really ups the value.

The insane power-to-weight ratio really great characteristic outside of the shop as well. When building a roadside kit or to-go tool bag for junkyard trips and other remote jobs, the key is to keep things simple but effective. You want to bring along as few tools as possible and will likely build your selection around 3/8-inch drive sockets. This lets you toss an impact wrench in the mix that’s actually capable of dealing with lug nuts and other larger fasteners. While walking around the junkyard, I hardly noticed the additional weight in my tool bag. And while I was lucky enough not to need it on a recent road trip in my ’69 Charger project, the small size did allow for me to build a fairly lightweight and space-efficient trunk tool kit. Even if I have a ton of trunk room to work with, it’s nice to have space to spare for cargo and other supplies.

Overall, the Milwaukee Gen II 3/8-inch drive impact wrenches are a big win for Milwaukee. They’re almost a cheat code for the minimalist because they work so well for so many occasions. Even pricing isn’t all that bad. $199.00 for the bare tool and the batteries to go with it will bring the total investment close to what you’ll pay for some high-torque impact wrenches—even more in some cases. However, the power-to-weight ratio really adds a ton of value to it. At 3.2 pounds, its a tool you can wield all day long and easily toss in a tool bag. The capability to dish out 550 foot-pounds of torque makes it an awesome choice as your primary impact wrench in professional and DIY settings. Again, you’ll rarely, if ever, call on the max-output of this thing. Still, it makes for a combination you’ll realistically get more use out of than many full-size models.