Editorial Review
When the inquisitive engineers at Milwaukee Tools started asking professional carpenters what they wanted in a portable circular saw, they consistently heard the same three things: pure cutting power, maximum control, and all-day comfort. The result of their research went into the creation of the Milwaukee 6391-21, arguably the best-built circular saw on the market.
For starters, the 6391 has a monster 15-amp, 5,800-rpm motor that produces 3-1/4 horsepower; that’s nearly as powerful as a worm-drive saw, yet this 7-1/4-inch Milwaukee model is more than one third lighter.
Look closely and you’ll notice that the blade is mounted on the left side of the motor. That southpaw position gives right-handed users a much clearer view of the cutting line since they no longer have to lean over their arm to see the blade. The 10.4-pound saw’s thick aluminum shoe tilts up to 50 degrees for bevel cutting.
The 6391 is also equipped with Milwaukee’s exclusive Tilt-Lok handle that can be adjusted to the most comfortable cutting position: to the rear for vertical cutting, on top for horizontal cutting, or anywhere in between. The saw comes with a carbide-tipped saw blade, blade wrench, storage case and owner’s manual. -- Joseph Truini
What’s in the Box
Circular saw, carbide-tipped saw blade, blade wrench, storage case, and owner’s manual.
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Customer Reviews
Not bad for the price 
2007-06-21
Decent power, certainly not worm drive torque though. It does well by compensating with speed. However, the blade guard continually gets caught on the the wood being cut, which is more than annoying. I'm thinking that for $30-40 more, the Bosch Magnesium may be better. Keep in mind, this is also not made in the US or Germany like many of Mil's previous products, it's hecho en Mexico...
I CAME ..... I SAWED ..... I CONQUERED! 
2007-04-09
I just finished building a storage building and ramp, using my new Milwaukee 6391-21 saw. The saw is VERY powerful, but easy to handle and adjustments are very easy to make. The unit exudes quality, in looks, sound and results.
Excellent Saw 2007-01-27
After much research I decided on the 6391 because of the blade left design. After using it on a few cuts I am already impressed with it. The saw is incredibly powerful. I swapped out the stock blade for a finish blade (note that it needed to be installed face down) to cut some stair treads I was using for a shelf. It went though my work like a hot knife through butter. I had to double check that I was actually cutting at first because the saw didn't even whine as it entered the material. Needless to say the saw has plenty of power. I think the lights actually dimmed in my basement when I pulled the trigger.
The case is fairly large but the saw fit in easily. There IS a space for spare blades in the bottom of the case. It will hold 4 or 5 blades which is more than enough for me. The lid of the case has a pocket to stow the manual as well as a slot for the blade wrench and one for the rip fence. (Note that there is a special fence for this model because of the blade left) I am not sure it they changed the case but mine does hold the saw and accessories with ease.
The real advantage is having the blade on the left. Being able to watch the blade enter the work and hold the line is very nice. If you have ever had a problem with wandering cuts I recommend this saw. I doubt I will ever buy another saw with the blade on the right. If my impressions of this one prove true I doubt I will ever have to replace this one.
Best circular saw I've ever used 2007-01-20
Really powerful and smooth saw, good stability. The saw's base is wide and of high quality. Easy to adjust. I prefer the blade on left for good visibility on long rips, although you might get a bit more dust in your face that way.
Light and does the job! 2006-11-11
I have been replaceing my subfloor in my kitchen and bath. I needed something lighter than my wormdrive circular saw. After reading the reviews on Amazon I decided to purchase this model for the light weight and power.
It has worked very well so far and the light weight is a relief to my arms.
The case does fit very snug,and I had a hard time getting it to go in until I found out to change the blade setting before putting it in the case and pushing down hard before snapping the lid shut. Probably the worse thing so far has been ajusting the depth of cut. The release lever seems to bind at times. It definally is a keeper.
Just what I wanted 2008-06-28
I already owned the right handed saw just like this one so I knew what to expect for the most part. I like the saw and it feels the same as the right handed milwaukee tilt-lok I bought 7 years ago (used it a lot since then too) as far as quality goes. I had been wanting this saw to be made for years and the other day I saw it online. I always wanted a left and right handed saw of the same brand and model to have on the job. I never cared for any porter cable tools and that is the only lefty saw I ever see anywhere anymore.
I like that it has a five year warranty in case something unexpected went wrong on it.
The case is nice and the wrench is standard but it does not come with a rip guide.
I use the saw both left and right handed depending on what I'm cutting and it is equally comfortable. I like that during right handed use I don't have to lean over to see the blade/ cut line. It does feel a little weird at first but your back will appreciate it if you are like me and your body is starting to age.
Another user said it was not safe for right handed use. I disagree, I have no problem but then again I have a lot of experience with saws and so forth as it is how I make my living- I believe in safety very strongly.
I would reccomend using a dewalt yellow rim blade. I like the 24t for framing and the 40t for finish. The blade that comes in the saw cuts good but throws material in the direction of your face a little too much for me. Dewalt has always made the best normal priced blade in my opinion. I like the Milwaukee saw though. Makita blades are ok too.
I would reccomend this saw to any other pro carpenter. If you build only decks you might want to go worm drive- nothing pulls a saw like wet pressure treated lumber. Don't get me wrong this saw has plenty of power and is plenty tough for all carpentry work on a daily use basis. I could just see someone who is putting it through max wet lumber duty daily could want the hypoid as the overall construction is a little more solid. On the plus this is an extremely powerful saw for it's size.
My old right handed one has helped me finish a lot of jobs. Milwaukee has always built a good product from my experience.
Great saw! 2008-01-07
No complaints at all. I love the adjustable handle angle. More than enough power for general carpentry needs. I'm not planning on using it on concrete or anything of that nature, so I can't comment on its performance in that category. The left-hand blade took some getting used to as my old saw was a cheap B&D model. Love it now.
only two choices for left blade saw 2007-11-24
I needed an alternative to my skil 77 wormdrive, it was either this or the Porter Cable so I went with this one. I am a pro, so I use it daily. So far it performs as expected. Mitre adjustment works well, depth adjustment works well. Havent tried the handle adjustment (and you probably never will either) The only negative seemed to be two raised indentations on the plate which needed to be filed down. Plenty of power, well balanced.
Ho Hum Saw 
2007-07-18
I have used this saw for four years working on my house. It has power. I have cut concrete, stucco, wonderboard, and lots of DF/HF and pressure treated lumber. The tilt handle thing is worthless to me--every time I adjust it, I seem to put it in the same place, where the handle is on all saws. Left cut is a poor idea for right handers. The real issue though, is that when I broke this saw and took it in for repairs, the repair cost made keeping the saw unrealistic. On a kick back I broke the gear housing. It was a careless setup on my part, but kick backs are going to happen, so there you go. Build quality on this saw is okay but not great. According to the repair folks, the problem is that quality is declining thanks to Chinese parts, but replacement part costs are higher than ever, thanks to Milwaukee. I just purchased a DeWalt 364K--it looks a little tougher. I need a sidewinder for some of my work, or I would just buy the HD77. The Milwaukee is okay, but really does not measure up against the big worm drive saws. The tool repair folks are not impressed with this saw, and they see them now and then.
Great Saw ! 2007-07-01
Tested a left handed saw - but didn't care for that manufacturer. A friend had a right-handed Milwaukee. Never bogged down. I'm a contractor and use this for cutting through wood (PT, plywood, pine 2x6, etc) also have cut through aluminum skinned panels. Like butter! I think I hear the saw laughing - looking for a challenge.
Do it right, buy it once and get on with your life.
