XM8 Project: Turn A HK SLR Into A G36

A Real H&K XM8 (top), Tommy Tactical conversion (bottom)

TommyBuilt Tactical is an 07/SOT FFL who specialize in customizing H&K rifles. They are busy working on a conversion kit to turn a H&K SLR rifle, the sporting version of the H&K G36, into a H&K XM8 look-alike.




The ill-fated XM8 was designed in that brief period of time when the military realized the value of modular rifles, but before the picatinny rail really took off to become the ultimate way to achieve this. This lead to its futurist design, that looks like it came straight from a hollywood prop supply company, lacking the “tactical” rails which adorn almost every surface of later rifles. It was also designed during that unfortunate period when gun designers thought integrating optics into a gun was a good way to shave a little weight off a rifle. If the XM8 program had not been cancelled, it would have faced strong competition from the FN SCAR, and even H&K’s own HK416, which arrived not long after.

Tommy tactical have not finished this project and so pricing is not available (despite writing this, I am seriously going to be getting about one email per month over the next year from excited fanboys asking about pricing).

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • mikewest007

    Tomy Tactical: inspiring dreams in those kids that are all grown up already? 😉

  • MC Robust

    Alright… I’ll ask.

    How much is it?


    Just kidding, man.

  • Mr.T

    XM-8 was a proper gun ,nowdays everyone seems to forget that you used to have full auto rifles that weigh just over 3kg , nowdays all that tacticool stuff with rails everywhere means that guns often weight much more even in carbine version . Now decide what is more important 4 rails or 100 rds of extra ammo

    • PCP

      It’s not that difficult to get an AR-15 to weight that even with a full fledged quad rail, you will just have to search a lot for the right parts and be willing to pay for them. Then you have modular handguards, in special the KeyMod pattern, that do basically the same and weight as little as a handguard can weight while being structurally sound; with those around it would be silly to go back to either a triangle handguard or a quad rail.

    • Bubblewhip

      The XM8 weighs more than an AR-15 of similar barrel length and thickness. The prototype has a 12.5 inch barrel and weighed 6.4 pounds with an objective of 5.7 pounds. A full medium or M4 profile 16 Inch AR-15 achieves that weight An example is the LaRue Predetar which is 6.25 lbs with a 16 inch barrel and free floating rail. Move that down to a 12.5 inch barrel with a short rail or plastic hand gaurd (which is basically a Carbon-15) it would weigh 5.5 pounds.(And people wonder why the XM8 was cancelled)

      • LCON

        But you fail to consider the optic with laser sights. It came standard with XM8.

        • Bubblewhip

          An Aimpoint t1 with mount and a AN/peq-15 adds about 14 ounces to the setup, hardly enough to justify the change in logistics, training, cost, and incompatibility with Stanag. The optic was also proprietary and was mounted in the absolute least ergonomic position for any red dot and laser. (far back to the rear) had no provisions to my knowledge of being able to replace it with something else if it came along unless it used HK’s proprietary mounting.

          • BOB

            not to mention this is just a haloesque g36, and G36’s have proven to be poo poo

          • Sweersa

            G36s have proven to be more reliable than most assault rifles out there, with maybe the exception of the AK series. It will easily beat a DI AR in a reliability test.

          • BOB

            It has a wandering zero that nothing can correct due to the decision to cheap out on the manufacturing process, in the hot dry conditions of the ME, its plastic furniture is known to expand and swell, noticeably, it’s ergos are not grea, when mounting an optic on its carry handle, the optic has a very high relationship to the bore axis, making obtaining a classic cheek-weld difficult to say the least… the list goes on. The modern AR is not perfect but its had a ton of its kinks worked out and the free market has come up with some excellent accessories and updates for it.

  • sianmink

    Too bad their conversion doesn’t seemto allow for a folding stock.

  • Callum King-Underwood

    That red one, interesting but ugly. Wonder what colours it will eventually be offered in

  • LCON

    XM8 was the KE module of what was then the XM29 HK and ATK broke them up and tried to market them on there own. Rails were still in existence its just someone thought they could do better. The ports on the side of the XM8 were not just vents they were PCAPS a system of mounts the army was fooling around with. You would mount your accessory to that and then mount that to the weapon. The optic on the XM8 was a insight integrated sight module. I think they still make them? It was in fact removable. I wonder if this replica uses the same sight. Anyway she is not that old they only killed it when 2004? And you can still see alot of XM8 in weapons like the ACR, SCAR, and a number of others. Its DNA lived on despite its stillbirth. And the XM29 Objective Individual Combat Weapon she was born from well another of its siblings is still alive and on its way back to the field. The M25 Counter defile engagement system aka the ATK’s the”Punisher”.

    • PCP

      I’m not so sure that much credit can be given to the XM8, being basically a G36 with a reworked receiver architecture, fancy spacey design and with the buffer plate transplanted to the stock for some reason I cannot fathom (with that the folding stock is gone). And even then you can’t credit the G36 beyond the guide spring layout; it’s action, the ACR’s and the SCAR’s are basically AR-18 derivatives with the notable exception of the SCAR using a piston system similar to the one used on the AUG (which I’m fairly sure do have some kind precedent I can’t recall).
      Quite frankly H&K should have saved time and money and insisted on the G36 as it is, or invested into a proper in-depth resign of the rifle.

      • LCON

        The History of the XM8 explains how she ended up both failing and looking the way she did. First that means a trip back to the 1960s the XM8 and G36 take there DNA as system weapons and the core of there operation from two Stoner weapons. The M63 and the AR18. Then we fast forward to the fall of the Berlin Wall. The sudden reunification of Germany forces the German army to kill the G11 program. A few years later Germany rebounded and the Germans decide its time to buy a new weapon. HK decided to play it safe and build newer and cheaper. They ditch the Delayed roller lock method and modify the piston of the AR18. They create the G36. To keep it simple they use a simple skeleton folding stock, design a AK style polymer magazine and build optics right in. Then the US Army puts out a request for a new weapon the Objective Individual Combat Weapon. A 20mm semiautomatic grenade launcher mated to a 5.56mm kinetic energy carbine. ATK teams with HK, HK takes there G36C and modified it loosing the stock, changing the magazine ditching the sights installing a side mounted charging handle and a electronic trigger device to allow use between the two parts. When PEO soldier weapons broke them up HK and ATK felt that at sometime in the future they would be reunited. This I think created part of its strange look. Then the army decided to try PCAPs and more weirdness occurred. The goal became to modify The KE module into a weapon that could do more then M4. It came close but still suffered. Part of that suffering was a lack of grasp of realistic threat needs. The XM8 DMR was the same caliber as the carbine version only with a longer barrel. This might have worked fine but in Afghanistan the ranges of engagement extended. The DMR also pulled double duty as the LMG this limited ammo and heat advantages being poorer then the M249. The baseline carbine was optimized as a clone of the G36K with a short barrel of 12.5inches which works fine in urban Iraq. It has a telescopic stock like M4, and there were plans for a folder but the army wanted unrealistic weight limits. the guard is rather large due to the the PCAP mounting system which additionally demanded a whole new catalog of accessories. The PDW was a good idea a shortened Barrel of 9″ offering a replacement for smgs and vehicle crew weapons that could easily be used but hardly anything not found in M4 series. The final nails in XM8s coffin the army forgot to cross its t’s and dot its I’s. Like the ACU they did not bother to Run XM8 through the proper competition feeling that as a subcomponent of the XM29 they could slip.it through on a technicality. They got cought. The solicitation process was forced on them when nobody else was ready and the school of infantry who is responsible for writing infantry mission needs felt a new LMG was better needed. Then the generals started fighting and away she went.
        In the case of ACR I point as a direct injection of XM8 DNA it was developed after the demise of the XM8 and has a lot of.features meant to correct perceived design issues of the XM8. The Malaysian version is a direct XM8 evolution, Charter Industries in Singapore has shown a.concept weapon that is a near clone.

        • PCP

          Well, I never really understood the claim about the superior modularity of XM8 or the different barrel lenghts in one package claims. It was never demonstrated that barrels and gas pistons could be changed on the field; that way it had no more modularity or padronization than the existing M4/M16 with perhaps the exception of a common stock (which isn’t that hard of a thing to do if you use an A5 system).

          I see both the SCAR and ACR as more of something that was bound to happen due to the desire to correct some issues with the M4/M16 platform that simply filled the niche the XM8 left vacant while taking from it advice on how not to do things. Get a proper receiver/trunnion, get a proper folding stock, use the accessory interface everyone else uses, think of a way to actually make barrel changes easy (or not that hard in the case of the SCAR, at least you have better return to zero and in a way it can be done “on the field”), build the thing from the ground up with realistic goals and guidelines, do not depend on the government to justify its existence.

          • LCON

            XM8 had three or four stock options, the telescopic seen above there was a folding option in the works that also telescoped then a simple flat but and version like the ones seen on SCAR pdw and HK416C. Really though you are right to a degree there was little it did that could not be made from a upgraded M4. The want to offer XM8 started with the same want of a improvement over AR15. Although to be fare there is little practical use of assault rifle barrel change in the field. When Remington offered ACR in the aborted IC they ditched the quick change as did most weapons offered.
            the only way I really could see a weapon like either XM8 or ACR replacing AR in the big army is if they moved away from 5.56×45 Nato, but the army has pretty much killed any notion of that.

  • The glorious videogame gun makes a triumphant return. It seemed for the longest time anything set in “the not too distant future” featured these monstrosities heavily.

    Curious whether a similar conversion will be feasible on the new G36 civilian models (HK291? I’m going from memory here)

    • Anonymoose

      >semi G36 in .308
      FUND IT.

    • Esh325

      The Ghost Recon 2 cover comes to mind.

  • therealgreenplease

    Please please please cost less than $3,000.

  • Edgar

    Congrats you made a copy of a worthless rifle. Figure like the SCAR after it these Euro attempts to buy the US military another 5.56mm rifle while we already had them, where pointless. But this is awesome for a collector who want a a cool civi legal weapons collection you did do a cool job.

  • Aaron

    If you like the look of the xm8 but aren’t rich it would be more interesting if someone(magpul) would make conversion kit for a ar-15. It would change the stock, grip(maybe), put a metal top rail that would also be the carrying handle like the xm8 and have hand guards designed to match with rails slots.
    It would be especially interesting with a side charging ar15 upper.

  • Andrey Martim

    The version of Malaysia seens to be useful in modern situations, as it is full of rails. But the XM8 is a nice firearm, albeit it is just a G36 in a different Shell.

  • mechamaster

    The ‘most interesting feature’ of xm 8 for me is ambidextrous hybrid magazine release ( finger operated or A/K style ) and bolt catch & bolt release button in the trigger guard area that G-36 doesn’t have in first place.

    • Mike

      couldn’t agree more!

    • Colin

      Am suprised that HK hasn’t updated the G36 with some of these XM8 features, the bolt hold / release being the most useful.

      • Sweersa

        HK has updated their G36 series with what you speak of. I just bought an XM8 style magazine and bolt release for my SL8-1/G36K conversion. HK puts them on new G36 rifles.

  • Erin Tarn

    Save these designs for when lasers can be weaponized. Otherwise, it’s just an ugly gun.

  • Azril @ Alex Vostox

    A little late here, But apparently the Elite Royal Malaysian Navy Paskal are confirmed and spotted using XM8. Picture taken during 2014 Independence Day parade.