Review: Upgrading The SCAR17S With KDG

It is not a secret that I am fond of my SCAR17S. The gun is just magic. With 168 gr BTHP I can put it in the hands of any non-shooter and they can hit steel at 200-300 yards with ease. My friend Greg saw the light at the 2015 FNH USA 3Gun Match when he tried my SCAR17S. Shooting off the bow of a small boat, he hit the 400 yard steel on the first shot. He even said “this is magic”. I just point it at targets and it hits them. So how could I improve this perfect weapon system? Kinetic Development Group Upgrades.

First up is the rail system. I have been running the Midwest Industries SCAR Rail extension since August 2013.


I like using the extended hand guard as I like to control the muzzle when I am shooting close range targets like the ones at the FNH USA 3Gun matches.




The Midwest Industries rail has its pros and cons. I liked it for the receiver height rail so I could mount my off set front sight as far forward as possible, but I rarely used my offset sights for accurate shots. The taller rail also made it harder to get my thumb over the bore.



The side rail made a nice ledge to rest my thumb. However the picatinny rail made this rough to hold. Personal preference I ended up using Magpul handstop kits and ladder rail covers to smoothen out the MI rail.



While the MI SCAR rail served me well, I have moved on to the KDG MREX 6.5″ MLOK rail.  With the lower top rail, I can mount lights or lasers without interfering with my sight plane.



A higher priority was the weight savings and how the hand guard feels in my support hand. The MREX only adds 3.7 oz to the gun whereas the MI rail added 8 oz; more than double the added weight of the MREX. Looking at the specs of the MI MLOK rail, it is lighter than my old MI rail but only by 0.5 oz. It adds 7.5 oz to the SCAR. The weight savings is instantly noticed with the KDG MREX when picking up the SCAR17S and supporting the front end.

The MREX rail is narrower than the MI hand guards. I can get my thumb over the bore and grab most of the rail. I feel like I am in more control of the barrel with the MREX.

DSC_0328 DSC_0332

The MREX replaces the side and bottom rails on the SCAR weapon system. With the side and bottom rails removed, you have a smooth contoured handguard. There are holes along the side in case the user wants to add rails, however I have never mounted anything that far back on the factory black polymer side rails. When I did mount something on the side, it would be near the front like in the photo above of my MI rail equipped SCAR. The bottom rail can be handy but again it is something I rarely used. When shooting Heavy Optics in FNH USA 3Gun matches, I cannot use a bipod. If I did, it would put me in Open Division. Shooting FNH USA 3Gun matches have helped push my skills and I can confidently hit targets out to 400 yards in rather short amount of time without the need for a bipod. So having rails on the bottom was just added bulk and weight I don’t need.

Using the KDG Kinekt 7 slot rail, I can mount my SureFire Hellfighter on the bottom.


HF Kinekt


Another KDG upgrade is the rear single point QD mount. I had originally modified my lower receiver using an Impact Weapons Component Mount and Slot QD mount. Which required drilling a hole in the polymer and installing the QD mount. While this worked, I found that I was routinely having to re-tighten the mount. Kinetic Development has one machined out of aluminum and can be attached to either side of the upper receiver.



The front QD mount by KDG is a little redundant if you are running the MREX rail, however it does work well as a indexing thumb rest. It is also ambidextrous and replaced the old snap hook loop attachment points behind the gas block.



The next major upgrade is the KDG SCAR Adaptable Stock (SAS) Kit. It is a Magpul ACR stock on a metal adapter. At $299.99 it is not cheap but if you want a stronger slimmer stock, it is not actually that expensive. The ACR stock alone costs around $160. Which makes the metal stock adapter/hinge cost around $140. Which is actually cheaper when you consider the cost of similar upgrades. Handl Defense has a metal stock hinge upgrade for the factory SCAR stock and it costs $180. VLTOR’s AR stock adapter for the SCAR is $169.95. With the KDG SAS Kit the stock is factory installed onto the metal adapter.

The ACR stock is slimmer than the SCAR stock and a little bit shorter when fully collapsed. The SCAR stock is fine but feels somewhat hollow yet bloated at the same time compared to the ACR stock.DSC_0309

The ACR stock has a Magpul QD cup that you can install on either the left or right side. I prefer having it on the right side for when I sling the SCAR17S with a two point sling.

The adjustable cheek riser is more pronounced on the factory SCAR stock than the ACR stock



The 6 position factory stock can’t beat the 7 positions of the ACR stock.




The butt pad is shorter on the ACR stock but not noticeable when shouldered.DSC_0314


While purely a cosmetic issue, replacing the SCAR stock avoids the infamous Ugg Boot resemblance.




The SCAR stock and ACR stock both have storage compartments for 2xCR123 batteries. The factory SCAR stock is behind the butt pad.




The ACR stock battery storage is in the cheek rest behind the hinge.



One added benefit to the KDG ACR stock adapter is the threaded hole. You can use a set screw to minimize any play the adapter will have with the SCAR receiver.  You can also see the stock hinge mechanism. When folded, the factory SCAR stock is held in place with the brass deflector. The ACR stock is held in place with the detent built into the hinge.



One last note about the KDG ACR stock adapter, I can swing the stock from folded to deployed and it snaps in position. The factory SCAR stock could not do that. I would have to press the stock catch when deploying the stock, otherwise I risk damaging the stock catch.


The KDG MREX rail and ACR stock make the SCAR not only look leaner but feels meaner. The rail is light and easy to grasp and control the barrel. The stock is solid and the metal receiver adapter is even more solid on the SCAR receiver. I am excited for these upgrades and will be testing it soon at a local two gun match.

Nicholas C

Co-Founder of KRISSTALK forums, an owner’s support group and all things KRISS Vector related. Nick found his passion through competitive shooting while living in NY. He participates in USPSA and 3Gun. He loves all things that shoots and flashlights. Really really bright flashlights.

Any questions please email him at


  • Alex D.

    Dude, we’re talking about a SCAR 17 here. If you want to sound impressive, try to make people hit steel at 800+ yards. Anyone with any service rifle can hit steel at 300 and all they have to do is not flinch.

    • Nicholas Chen

      Not for novice shooters and talk to any joe schmoe hunter. They think a 100 yard deer shot is far. They rarely shoot out to 200-300 yards When they do, they need a bench rest or a bipod and take FOREVER to take that shot. I am talking about making hits on steel with the first shot and every shot in short amount of time. Standing, off hand, barricade trapped. It doesnt matter. This gun can do it and I have done it. I cannot do that with my ARs. Watching over 200 shooters at FNH USA 3Gun, it is common to take a few shots at targets past 200 yards with ARs to get a hit on steel. Not the case with this SCAR17S.

      • CommonSense23

        Curious what size steel you are shooting at that requires two to three shots from a AR but not from a SCAR.

        • Nicholas Chen

          Most of it is due to the shooter. They are missing the target. 150-200 yards is 6 inch steel. at around 300 it is 8 inch and 400 is 10-12 inch.

          • 11B

            Ok, now that you say 8 inch plate @ 300 that’s a bit more challenging. I was thinking just a man sized silhouette

          • Nicholas Chen

            Also those long range targets are not shot from a table or prone. You are usually shooting in some unstable postion. Add like 30 pistol and shotgun targets to 6-8 long range targets then do it all in under 3 mins.

          • CommonSense23

            I have spent a lot of time with the MK17 and don’t see how someone is going to routinely shoot better than a quality AR10.

          • Nicholas Chen

            I have only shot a handful of 308 rifles. The best was a Larue PredatOBR but it was very heavy. I liked it because I could see the 300 yard gong, I was shooting, through the recoil impulse. My SCAR jumps a bit.

            Different strokes for different folks. For what I use my SCAR for, it works great. recoil is the softest of all the 308 I have shot. I am biased LOL

          • LilWolfy

            Roger that. The SCAR-17 sacrificed accuracy for lightweight with that barrel profile and operating system they’re using.

          • LilWolfy

            With the last SCAR-17 we were shooting, I couldn’t get hits on 18″ steel but one time out of 10 at 600yds.

            With an AR15 even in .223 Rem with 77gr, I’m 9/10 in the same conditions (no wind value that day). At that same range, I’ve shot a 2.5″ group at 600yds with a custom Krieger-barreled AR15, at night even.

        • LilWolfy

          When shooting steel pepper poppers, even at 100yds, 5.56 has to be hammered (2 rapid shots) on the head to get plates to fall, depending on how the plates are set up.

          With 7.62 NATO, the whole pepper popper and base goes tumbling over, and I have seen this over and over throughout the course of a career running lots of live fire training or competitions.

          The added recoil and muzzle blast from the 7.62 rifles presents a problem though, so an ideal solution would be an AR15 with light recoil, shooting something heavier with a really high BC.

          And now you see why I ditched the .308/7.62 NATO in favor of 6.5 Grendel. Run the numbers with that popular 168gr SMK match ammo, with Bryan Litz’s real world BC data (.437 G1), versus a 123gr SMK from the Grendel (.522 G1 BC).

    • Mc Cain

      I love getting my AR precision rifle out and banging the steel out at 800 yards with it, shooting fast enough to get the steel target swinging.

      The SCAR is an awesome rifle, but …. for serious long distance shooting with the .308 I prefer my GA Precision Crusader.

      • Nicholas Chen

        Oh no doubt. There are better rifles out there. But for a 16″ barreled battle rifle the SCAR17S is no slouch and it can go out to 800 meters, according to my Army Sniper friend. I have only tried it out to 650 yards. 10 hits all on steel. It was a torso target though. But a nice personal best for my shooting skills.

      • 360_AD

        How long is that barrel on the GAP? how heavy is it? Case closed.

        • Mc Cain

          Long and heavy.

          My precision AR has a 20″ White Oak Armory on it.

          It put rounds into a 1/2″ group at 100″

          The GA put them into a group less than a dime size.

          Love ’em both.

    • 11B

      Just what I was thinking- especially with that optic! Even iron sights out to 300m is fairly easy in the prone for most people on a man sized target.

      • Nicholas Chen

        For some but not all. I have a hard time with irons and 5.56 out at distance. The SCAR17S is stupid easy.

        • Trayvon


  • Anonymoose

    Could an ACR model PRS be mounted on a SCAR 17?

    • Nicholas Chen

      I don’t think so. The PRS ACR stock is a fixed stock. So it’s attachment method is proprietary on the ACR. You could get a VLTOR RE-SCAR buffer tube adapter for $160 and then get a regular PRS stock. I am not a 100% sure if the VLTOR can do it though. HDD makes an adapter to use a PRS stock on a SCAR17.

  • Ross

    $600 in adders to the $3000 rifle… Yeah, I’m planning on both eventually.

    • Nicholas Chen

      Well my SCAR was $2600. Other handguards are around the $200-$300 price range. The Handl carbon fiber handguard is $500

      • Ross

        I think I paid 2750 for mine. But yeah, I like the look of the MREX and the ACR stock. Both were bookmarked in my favorites for future considerations.

        If the SCAR starts getting heavy use next summer I’m sure I’ll pick them up.

        Does the ACR stock comb come as high as the stock SCAR? It doesn’t look like it. I keep mine in the high position and don’t like the bendy nature of that piece when extended.

        And I didn’t know the butt pad came off to store things. Thanks

        • Nicholas Chen

          No the ACR cheek riser does not come up as high as the factory stock. I never used the factory one, but I use the ACR one.

  • Joshua

    I’ll never understand the love for the SCAR. It’s a mediocre platform.

    I do however find it amusing that the only good thing the ACR did was the stock.

    • Esoteric_Arms

      Mediocre cause you cant afford it? I’m dying to hear your response as to why you think that

      • Joshua

        Mediocre because I was issued one for free and had the luxury of being supplied free ammo, and using it in combat zones.

        It’s a mediocre platform that is currently being phased out by better rifles.

        • Anon

          I’m sure you were Mr. tier one oper8r, so what are these better rifles

          • Joshua

            The M110K1 is the current rifle replacing it. MARSOC started it and everyone has slowly been replacing the Mk17 as well.

            It takes a bit due to the lack of production capability of KAC, but K1 kits are working their way through the pipeline.

            I also wasn’t “tier one” that would be more SEALs and such, I wasn’t that cool.

        • CommonSense23

          You just insulted the SCAR. How dare you insult one of the most overrated rifles of all time. A rifle that only had to be better than the MK14 rifle it replaces. A rifle that none of the SMUs decided to use. That the Rangers abandoned to go back to the M4.

          • Joshua

            I know, its such a special operator rifle that insulting the operator aspect of an operators rifle is just insulting to the operator of the operators rifle.

            I hang my head in shame.

          • st4

            You got lucky. If it was the Hk416 you had insulted instead, you’d have to commit seppuku on the spot.

  • Iggy

    “So having rails on the bottom was just added bulk and weight I don’t need” – but the miniature anti-aircraft spotlight is essential?

    • Nicholas Chen

      It depends on what I am shooting and how far. The Hellfighter is used for long range night shoots and acts as a monopod.

      When shooting 3gun, I don’t use lights.

  • I have never been a fan of the SCAR since its a pig. I would like to see what one of these feel like but I’m guessing its not something I will every bother spending money on since I still like very light rifles.

    • Steve

      Name another battle rifle lighter than 8 lbs empty…

      Some of the older AR-10 style rifles might qualify, but once you start adding rails and such…

      I sold a Mk14 clone to get mine – it was close to 11 lbs unloaded.

      • Rails are over rated and over used on today’s guns.

        • Steve

          My question stands… the SCAR is a lot of things, but heavy isn’t one of them.

          • As a 308 rifle the weight is fine, as a 5.56 assault rifle its a pig.

          • Nicholas Chen

            Yes. I am not a fan of the SCAR16S. The 308 version is great. It can hold its own against a lot of AR10s. Not many 16″ bbl AR10 can compete against it in terms of weight, accuracy and recoil.

      • st4

        Great minds think alike. I ditched my EBR as well for the 17S. That thing was a boat anchor.

  • Tyler McCommon

    Ah you’ve made a $3k gun into a $4k gun.

    • thedonn007

      I would love to own a SCAR-17 as well, but I just cannot justify the cost. Especially if I have to spend another $1,000 to make it better.

      • Esoteric_Arms

        The only thing a SCAR needs to make it better is a new trigger and that’s it. All this other crap is not needed

        • Nicholas Chen

          Already have the Geissele Super SCAR trigger.

          • Esoteric_Arms

            Love my GSST

        • Steve

          If you’ve got a scope or bulky optic, having an angled charging handle is a good way to save your knuckles, as well. Having sliced my hand open charging an AUG two years ago at SHOT (on a sharp, bare aluminum, prototype scope mount), I’ll gladly trade $20-30 to not do that again…

          When I got my SCAR 17S, the day 1 changes were Geissele trigger, IWC charging handle, AAC MITER flash hider (personal preference), and a Nightforce 2.5-10×24 in an ADM mount.

          Beyond that, I’m eyeing the KDG stock reviewed above. I played with the kit at a local gun show and it was REALLY nice!

          I’ve got a few other gadgets in my spare parts box, such as rail panels and VFGs, but I’ll probably play with those for a range trip then take ’em off. Those things tend to annoy me more than anything else.

      • Nicholas Chen

        It all depends on what you want out of the gun. I run and gun with my SCAR so I prefer using an extended rail. Most rails will cost you in the $200-400 range. The factory stock is perfectly fine. But when competing, you look for any advantage. And I will be honest, the stock looks better. Is it a huge difference? Depends on the person using it and what they want.

        Most of the cost is the stock and rail. That is $600, not $1000. Unless you add the cost of the scope.

        • thedonn007

          Sorry, I thought you had an aftermarket lower that took the SR25 mags. Really, I have no need for such a rifle, but I still want one.

          • Nicholas Chen

            Nope. Stock lower. There are some limits to what I spend on this gun. $400+ to use AR10 mags is not appealing to me.

      • Tyler McCommon

        I’d love to own one too but spending $5k on a gun, upgrades and optics would cost more than my collection combined x3

  • Aaron

    What a difference the ACR stock makes cosmetically, what mag is that in the first photo? Beautiful rifle Nicholas

    • Nicholas Chen

      Thanks. It is the Molon Labe 25 rd mag. It isnt very reliable. I use it as a magpod, as you can see in the pic. I prefer the Moses Mag SCAR17 mags and FNH factory mags.

  • BattleshipGrey

    I’ve always hated the look of the original SCAR stock. That ACR version looks much better.

  • Esoteric_Arms

    Save some money and get a VSS-11 Stock. It makes the Scar stock solid

    • Nicholas Chen

      Not a fan of the VLTOR aesthetics. Like the CASV-SCAR rail looks like an erector set on the end of the gun.

      • Esoteric_Arms

        Didn’t say the rail. The points you posted about the Midway rail are valid but to me the stock is a little pricey for what you get and I think it makes the gun look goofy. (that’s my baby)

        • Nicholas Chen

          To each his own. Out of curiosity, why is your red dot so far forward?

          • Joshua

            Yeah that makes no sense with the magnifier that far to the rear.

            They are supposed to against each other, but I know you know this.

          • Esoteric_Arms

            Joshua if you had one you would know it does make sense. Do a quick google search and I’m not the only one having this problem.

            Also eye relief is a big deal on this 3x mag and needs to be closer to my face.

            As far for the QD swivel. I use a Magpul MS3 with a QD attachment point. Where I attach when shooting is right below the stock (as a single point). When I want to sling it out of the way (like a two point) I detach the MS3 and connect to that second point. Hope that makes sense.

            As for you calling me out as someone who docent actually shoot it … well this is the internet ..

          • Esoteric_Arms

            The first picture is with the 3x where I have it in the picture and the second is with the T1 and 3x close but not touching. Its harder to see in the camera but its still there . The second picture notice how the red dot is more star like where as the first picture (T1 forward) is more crisp. I dont use the 3x often so the star is not a huge factor. Where I place my T1 has zero affect on my shooting. I could have it all the way forward the only downside would be the “weight”. its a red dot people

          • Esoteric_Arms

            I never thought of it as “so far forward” also since its a red dot I was unaware there was a “has to be” position. Its comfortable on my eyes cause reduces the outer black ring of my T1.

            The biggest reason is when I use my 3x mag the closer the T1 was to it the more smudged the red dot was. That was my solution to reduce it. I have read that the new T2 does not create the smudged red dot. (by smudge I mean not as crisp)

          • Nicholas Chen

            This is why I ask. I dont use a magnifier so I like as wide a field of view as possible. So my red dots tend to be closer to my face.

          • All the Raindrops

            Wide FOV on a red dot is unnecessary. As long as you can repeatably shoulder rifle and see the dot, it could be a 5mm tube. Anytime anyone complains about FOV on a red dot, you know they’re not shooting both eyes open. :/

        • Sam

          Why do you have a beluga whale attached to the end of your rifle?

        • David

          That is an ugly sumbitch.

  • Mike

    Where can I find the test that shows the Bushmaster ACR stock is stronger than the SCAR stock?

  • iksnilol

    Uh, it is a 308… 200-300 yards isn’t really impressive with 308.


    • Nicholas Chen

      For a beginner shooter? Yes it is.

      • LilWolfy

        On the same day, I took a total new, never shot long range before female shooter, and had her hitting center at 600yds with a 16″ 6.5 Grendel, like it was fun or something.

        And I, with decades of long range shooting, multiple formal military sniper courses including SOTIC, sniper instructor training, international placement in competitions, could not make predictable hits with her husband’s SCAR-17 at even 500yds on 18″ steel in no wind value conditions.

        • Nicholas Chen

          Here is the target I hit at 650 yards. With the SCAR in the picture above. I was using Freedom Munitions 168 BTHP.

          • LilWolfy

            Nice. If you read what I said, I have had SCAR-17s that we could hit out to 800yds with, (using SSA 168g BTHP load, and NightForce optics, Geissele trigger).

            The last stock SCAR-17S was all over the place at 600yds for me, and I can hold very consistently under .75 MOA at that range in those conditions with a capable rifle, usually more in the 1/2 MOA accuracy.

            My GAP semi auto .260 Rem will shoot 1/2 MOA at 1000yds with 130gr Berger VLD, but it weighs twice what the SCAR-17 does.

        • Nicholas Chen

          Here is a video of me hitting 650 yards. I dont have decades of shooting, let alone long range shooting. I have only been shooting since 2012.

  • Trayvon

    Needs more storage for Skittles.

  • Steve

    I’ve got plans to pick up the stock, but contacted KDG regarding the short rail they sell. It will fit the 13″ barrel kit that FNH sells, but it limits your selection of muzzle device. Since running a can is not really a ‘maybe’ with a 13″ .308, I’ll probably keep the original handguard/rails.

  • JumpIf NotZero

    As a photographer, and a designer, and someone who has done color matching…

    That gun has 6 shades of tan on it… It’s infuriating and appealing at the same time 😀

    • andrey kireev

      Fifty Shades of SCAR

    • Nicholas Chen

      I call it “Cornucopia of Tan” It doesnt bother me.

  • Nocternus

    Why put a scope and Magpul Pro peep backup sights on the same weapon? I would want my backup sights to fill a role that my primary optic lacked in. Scope for long range and back up for close to medium range. Perhaps it is just preferences though.

    • Nicholas Chen

      This gun is setup for how I shoot 3Gun matches. I shoot Heavy Optics. I am allowed irons and a magnified optic. The MBUS offsets are sighted in for close range. However they will not work in the same plane as a 4-16x scope. So I went with offset.
      Have you tried looking through irons in a scope? Your front sight blurs out.

      • Nocternus

        Oh i get the reason for the offset. I guess it is dependent on MOU. Perhaps the peeps work for competition. I just prefer my offset BUS to add a functionality that my primary optic is lacking. Personally I went with the XS sights they allow me to get a fast target acquisition and work well for short to medium range. To each their own though.

  • nonsinum

    niet! rifle is fine

  • Chris

    Which sunglasses did he wear on the second photo?

    • Nicholas Chen

      Those are my Oakley S.I. Gas Cans. I use them for daily wear and they are rated as eye protection. However for competition I use the new Oakley S.I. Tombstones.

  • supergun

    Beautiful weapon. I still like my COLT CRX Competition AR 15 hand built in Texas less than a $1,000.

  • All the Raindrops

    308 for 3 gun?

  • Jesse Foust

    Not hating, but saying the $300 stock upgrade is “not cheap” immediately after showing a $5000 flashlight mounted seems kind of ludicrous. All in all though, it’s a fine looking gun. Thanks for the review.

  • LilWolfy

    “With 168 gr BTHP I can put it in the hands of any non-shooter and they can hit steel at 200-300 yards with ease.”

    This has been my experience with the SCAR as well, which is nothing to write home about. Once you start pushing the distance out, the patterns formed by the POI are all over the place. Some rifles will hold better accuracy, but you’re really rolling the dice.

    I’ve had guns come through long range courses that held well out to 800yds, and others that are unpredictable at 600yds with patterning. You really do need a better trigger in the SCAR to make it even come into play at distance.