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I love my Remington 700 AAC-SD rifle, but it had some issues. The lack of a free-floating barrel, the sucky cheek rest (solved via workaround), the inability to use Accuracy International magazines…. The totality of those issues had me looking at options for replacement stocks. With the possibility of getting my hands on an XM2010 chassis getting even more remote, I was getting ready to pull the trigger on a McMilian stock when Maarten from MDT dropped us an email and asked us to try out his nifty chassis system. And boy, was I impressed . . .

The concept is phenomenal. Take a standard Remington 700, drop it into this chassis, and you instantly have a rifle that almost rivals Remington’s XM2010 in terms of features. All you need in addition to a rifle and the chassis is a buttstock assembly and pistol grip for the AR-15 rifle and you’re good to go. And thanks to the adaptability of AR-15 parts, the rifle can be adjusted to exactly fit your specific body type.

In concept, that is. In practice, getting the thing assembled takes some work.

The chassis comes in three parts; the receiver block, the trigger guard/magazine assembly and the forend. In order to get your existing rifle into the chassis you’ll need to temporarily remove the trigger and permanently remove the bolt stop, a process which involves drifting out the trigger pins.

I’ve done it before, and watched as my stock Remington 700 trigger exploded all over my workbench when I removed the punch (having forgotten to install the replacement pin that holds the trigger together). If you’re not mechanically inclined, you might want to take the rifle to a gunsmith to have them do the install for you. Thankfully, the chassis kit includes two small pins that will hold the trigger together while you swap stuff around.

To me, the installation process was so daunting that I was only willing to do it after I had saved up enough money to satisfy MDT should they want the thing back. This was going to be a one way process for my gun, win or lose, as I didn’t fancy the idea of drifting the pins out again to send the chassis back.

But once the chassis’s installed, you really wouldn’t ever want to go back.


Thanks to the folks at Magpul, I had a PRS rifle stock to put on the rifle And with the ergos of an AR-15, the gun feel SO much better. There’s a damn good reason why in-line stocks and adjustable cheek risers are popular, and it makes the Remington 700 a much more user friendly rifle.

It even looks sexier. I had people coming up to me on the rifle range complimenting me on my fine-ass gun, asking me what it was. Putting the Remington 700 in the TAC21 chassis makes it look like some sort of spacegun instead of the $600 bolt action rifle it really is. “Why is that guy over here on the 100 yard range?” I heard the guy next to me ask his friend. “He should be over on the 500 yard line, at least.”

While the ergonomics may have been miles better, the real “killer feature” of the chassis for me was the free floating barrel. Charlie Sisk is a big fan of strapping the action of his custom Remington 700 rifles as deeply into a big block of aluminum as he can, and he seems to be doing well with that approach. MDT, on the other hand, has taken more of a laissez-faire approach to the action with only about three contact points between it and the chassis. This lets the action and barrel flex more, but doesn’t seem to negatively impact accuracy. In fact, just the opposite. What used to be a 1 MoA rifle has become a 1/2 MoA rifle.

At the beginning of my range session, I put five or six rounds of Federal Premium into a hole about 1/2 inch in diameter at 100 yards with no problem. But, as the day went on, I started having issues. The rifle would swing wildly from being 2 mils low to 2 mils high without me touching the turrets. I thought it might be an problem with the temperature of the barrel, but when I went to tap the barrel to see if it was hot, it wiggled in the chassis. It had come loose, and I had left my wrenches at home.

One liberal application of Loctite and a severe torqueing of the screws later and the problem has been solved, but it sure was annoying. Just FYI for all you prospective buyers out there.

MTD TAC21, c Nick Leghorn

My second favorite feature, after accuracy, is the detachable magazines. The chassis takes standard Accuracy International mags and I think that’s just damn nifty. There’s no logical reason why, I just think it’s really cool and looks awesome.

Also very nice: the entire back section of the rifle comes off. The stock is attached using a tail cap that slides over the back of the rifle, and is held in place by a chunky rotating pin. This lets you remove the back section for cleaning or transportation, making the overall length of the rifle very small for transportation.

Is it worth the money? In my opinion, yes. No other chassis on the market gives you this level of modularity and adaptability while keeping the weight down to a reasonable level. You’re looking at about $1,700 for the full rifle when complete (well, without optics), but with only the addition of this chassis you can shoot as well if not better than rifles costing twice that price.


MDT TAC21 Rifle Chassis for Remington 700 Rifles
Price: $700 (short action) / $800 (long action)

Ratings (out of five):

Feel & Function * * * * *
AR-15 ergonomics in a .308 bolt action rifle? Sign me up!

Ease of Use * * *
Any time the instruction manual requires you to get out your punch set, that immediately knocks off a star or two. For this chassis, getting everything together was such a pain in the ass that I wanted to knock this down to two stars. But considering how amazingly it works when you’re done, I’ll leave it at three.

Overall * * * *
Yes, it’s a pain to put together, but when you’re done you have a high quality precision rifle on your hands.

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    • I actually like the AICS a little more from the aesthetic perspective, but, yes, this thing is damned pretty.

  1. When I read the lede paragraph about turning a Rem 700 into an AR, I thought “Tacticool Foghorn is tacticool”. Then I saw the video. And I must have one.

  2. Good review. At that price point, without a mag & a stock, then why not just get the actual AICS?

  3. Anyone know if one of these world work with a 700 Sendero chambered in the 7mm Rem Mag?

    • Found it…in stock, and I get paid in 32 hours?! BAh! 10 round mags on backorder. >.>

  4. I was thinking about waiting on Mossberg to make an MVP in .308 but this? I may just save my pennies for this instead.

      • No Joke.

        New Coke. Crystal Pepsi. Lazenby as Bond. Those were all bad ideas. Mounting a scope for a precision rifle build to the effing chassis trumps all those.

        No thanks. I’ll keep mounting my scopes to 20 MOA steel rails torqued to the proper spec on the actual receiver. You know, the way it should be mounted.

        • You need to have a reason to back this opinion up. This action is sucked tight into this chassis, which is integral to the rail. My accuracy improved substantially after installing in this chassis.

  5. Makes it look *vaguely* like a G36 rifle, at least the front end.

    Very interesting. Not sure I’d be up for the install myself, but definitely a cool piece.

  6. I had one (AAC SD as well, btw). I thought I loved it, then went out and shot it.
    Unpredictable performance. Even with the loctiting and torquing to hell you mentioned (which I did, as well).

    The chassis rail system use, instead of using the mount on the action, probably doesn’t help matters.

    I’ve since gotten rid of it and replaced it with the Evolution Chassis system from XLR Industries. I couldn’t be happier. Sure, not as “space gunny” (Hey. I like space-gunny, too. lol)as the Tac-21, but still looks great and performs flawlessly. Zero issues.

    Now, having said that, I do like the owners of MDT. They are VERY nice people, but this system, just was a no-go, for me.

    Also, if you want to tighten up that PRS stock, I know a trick. If it isn’t loose yet, it will be after a few range days. Basically, you can make a gasket to make up the difference between the stock-adapter and the back of the chassis body, where the pin holds them together. Another little annoyance that I noted.

    • Yeah, it’s already starting to come a bit loose. But there’s a gasket that came with the stock, I haven’t tried using that yet.

      Right now, I really like it. If my opinion changes in a couple months (IE if I see the same issues you talk about) I’ll update the review accordingly.

      • Oh they include a gasket now? Kewl. I did suggest that to them. I guess they took it to heart. I do like that at least they listen and are trying. Maybe eventually, it’ll be something I can look at again.

    • “The chassis rail system use, instead of using the mount on the action, probably doesn’t help matters”

      Why would this matter, if action and scope mounted so as to not move (torqued down).
      I’ve seen scope bases that needed to be bedded or screw holes out of line with axis of action.
      I could see if height over bore was an issue….

  7. After a lot of research I decided that the AICS might be the better buy, but then I might just sell the SD

  8. coming from a background of European automotive performance engineering, I am appalled at the simple mechanical tasks people in the gun realm find difficult. it’s laughable to me that anyone would consider installing a rifle into a chassis like this a pain in the ass. rating it at 3/5 for ease of use because you need to punch out a couple pins is absurd…

    • Indeed. Building an AR from scratch poses little challenge, yet most will buy brand name rifles or pre-assembled lowers and uppers. This assembly is child’s play by comparison.

  9. Mr. Leghorn-

    Have you had a chance to compare this to (or have you heard anything about) JP rifles JP-AMCS modular chassis for the rem 700? would like your opinion.

  10. Saw these photos posted over on r/longrange, and I’m awfully curious: could you use that Law Tactical AR-15 folding stock adapter on this to reduce its size? That’d be pretty damn slick if you could.

  11. Just got one of these in 300 win. It’s my first gun. Got a top of range vortex put scope and I Sighted it in at 100 yards within 10 minutes with no previous experience. I love it worth every cent.

    • Looking to buy the TAC 21 but curious to know if this is the best chassis for the money?

  12. What a waste of a tactical bolt on a chassis like that. Ya lets put a precision bolt rifle on a over-priced semi-auto ar type chassis and stock and hope for the best. There is a reason nobody is buying the stock rem 700 tactical chassis package, and all the builders out there building this exact monstrosity all seem to be selling them. If you are going this route stick to ar-10, if you are going traditional bolt stick to McMillian, H&S and Bell Carlson. And what’s with the scope mounted to chassis? Amateur hour.

    • I don’t understand why so many people are against the scope being mounted to the rails on the chassis. The XM2010 is a similar setup and has no issues.

  13. Fired nearly this same rifle at a match a few weeks back (in .308 Federal Gold Medal). Accuracy was spot on and I was easily able to hold 1 MOA groups at 550yd under varying wind and temperature conditions and rapid fire (so, effectively probably 1/2 MOA gun). My ONLY grievance with this stock is the butt pad. After 60 or so rounds in the rapid (prone w/o butt spike/sock/etc.) my shoulder had the distinct imprint of the very tough butt pad (you could make a mold in my skin and duplicate the design). So if you’re going to be shooting 50+ rounds I would highly suggest looking at the possibility of replacing or modifying the butt pad, especially if you’re going to be going more than .308. The safety becomes basically useless when in your final firing position and cannot be viewed from your peripheral vision (I just left it on fire all day w/ a chamber flag anyway).

  14. I have the same set up. Couldn’t believe the difference it made. Had a over mold stock shooting 300yds at 6in plate. No prob. Now I hang golf balls to hit. Moving out to 500yds on 6in square now. Will hang some golf balls.???

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