Milwaukee Gen II M12 Stubby Impact Wrench Hands-on Review: All the Grunt and Grace

Milwaukee’s Gen II M12 Stubby impact wrench is ridiculously powerful for something its size. I usually like to start these tool reviews with some sort of narrative or by talking about a project I’m using them for. This time, it’s just too hard to think about anything other than the absurdity of this impact wrench. 

We’ve all been watching cordless tools get more and more powerful in smaller and smaller packages. While manufacturers will continue to hone their edge and push this trend, the latest M12 Stubby impact wrench feels a lot like the point all roads are leading to. 

Milwaukee sent the Gen II M12 stubby impact my way for review. It arrived ahead of its release, right as I tore into my latest project of reviving my work truck. That rig needs a lot of help, including some engine work. If you’re familiar with the 2003 Ram 1500s, you know there are a lot of bolts that need to come out in order for me to access the power plant. 

From the biggest, gnarliest, rustiest bolts to the smallest, daintiest nuts, the Gen II M12 Stubby had both the grunt and grace to get through them all without trouble. I will go through my full thoughts in the review portion. But, I’ll say it right now, this is one of those tools that’s so good that everyone needs to check it out. 

Big Oomph In a Little Package 

Yeah. It’s a little 12-volt impact wrench. Some of you might be quick to poke fun at that. But here’s the deal: It’s capable of delivering 550 foot-pounds of breakaway torque. Who’s laughing now? 

That’s some serious power for an impact wrench that’s smaller than even some screw guns. The Gen II M12 Stubby impact fits right in the palm of your hand. It weighs 2.2 pounds without a battery and 2.7 pounds with a 2.5 Ah battery. 

Being the second generation of this tool, Milwaukee did carry over some details from the last model. The 4-mode drive control is back. Three of the modes are high, medium, and low, with the fourth being the Auto-Shut-off mode. Selection is a bit different than the old push-button toggle. To change the mode, you set the directional switch to the neutral setting. From there, you pull the trigger, which cycles through the four modes.

Other carry-over features include the LED light built into the head, the battery gauge, and even the value. Despite what you might assume, the retail price of the bare tool is $199.00. That’s pretty great for a tool you’ll get as much use out of as this. 

Again, the Gen II M12 Stubby impact still has yet to hit the shelves. Some retailers are accepting pre orders with shipping expected to start in early October. It’ll also be available in both 3/8-inch and 1/2-inch drive versions—I’m reviewing the latter today. 

Does It Actually Have the Grunt

As many good things as I’ve been saying about Milwaukee lately, I’m not some die-hard fanboy. I also haven’t been paid to say them, nor have any sort of behind-the-scenes deals been made in exchange for my favoritism. I just like good tools, and it’s been on a roll lately. Still, I am skeptical by nature. Naturally, an eyebrow raised when I read the specs on this thing. 550 foot-pounds from something this small seems too good to be true. 

I immediately put that power rating to the test upon this tool’s arrival. I did so by setting my Craftsman torque wrench to 250-foot pounds—the highest it’ll go—and torqued down a lug nut on my project truck. You can see in the video that it tore the fastener off with just a little bit of work. Based on that test, I feel confident in the advertised power rating. And even if it were to fall short, it can still deliver more than enough mid-range power to make the M12 Stubby impact wrench incredibly useful. 

Of course, my hands-on testing didn’t conclude there. As I said, that truck needs some engine work. It developed a sound that I initially thought to be a rod knock. I tore the oil pan to take a closer look. On this truck, that entails removing the torsion bar crossmember. The bolts holding it in place are incredibly rusty, and the superb power came in handy with tearing them free. After that, I was able to set the Gen II M12 Stubby Impact to a lower setting and quickly remove the oil pan bolts without risk of damage. 

Thankfully, I didn’t find anything alarming in the oil pan that would signify a spun rod bearing. So, I turned my attention to the top end to inspect the valve train. Accessing it once again called on the more delicate nature of the M12 Stubby impact wrench. Initially, I thought I’d caught a break when I found most of the lifters had collapsed, which would be a relatively simple fix. Then, I found coolant in the number 2 cylinder that warrants a complete top-end tear-down. Of course, I used the M12 Stubby to tear the nose off the truck in preparation for it. 

The Verdict 

It’s hard to believe that the M12 Gen II Stubby Impact wrench can deliver as much power as it can from such a small package. Even when compared to my DeWalt Atomic impact, which I love for the same reasons, this thing is crazy small despite being far more powerful. That’s thanks to the 12-volt battery compared the DeWalt’s 20-volt.  

Will the Gen II M12 Stubby impact replace your full-size 1/2-inch impact? No. Even if it can pump out serious power, I do think pushing it to those upper limits on a regular basis is asking for it to kill over in short order. At the end of the day, it is a small tool. That’s OK, though, because that increase in top-end power does translate to an increase in mid-range performance. And that’s what makes this tool really, really good. 

You can sneak this thing into tight spaces and work through fasteners with ease all day long without even a hint of fatigue. When you do run into those stubborn bolts that love to ruin days, as I did on the torsion bar cross member, it has the extra oomph you need to keep moving. This combination of characteristics makes for an impact wrench you will get more use out of than any other. 

Battery life is also pretty impressive. I expected this thing to go through the little 12-volt batteries like candy, but it’s not that bad. I still have half a charge on my 2.5 Ah battery after all of this testing without recharging. Moving to a 4.0 Ah or larger battery will make it even better, but you can keep that slim handle with the smaller batteries and still have a relatively pain-free experience. 

All of that being said, the latest generation of the M12 stubby impact wrench is not too good to be true. If you’re serious about working on cars as a DIYer or professional, you really ought to check it out when it hits the shelf in October.