XM8 Assault Rifle

I’ve mentioned before that the biggest search engine draw to MO has been the XM8 assault rifle. Stryker searches bring in a lot, as well, but I’ve got an entire category devoted to the new combat vehicle and only one post about the new rifle.

Folks must be desperate for info on this baby. For a basic intro to the XM8, go to my previous post.


The XM8 (M8 if it’s adopted) assault rifle is a proposed replacement for the current M16 rifle and M4 carbine, the standard infantry weapons in today’s US military. The XM8 action is based upon the Hechler & Koch G36, a tried and true infantry weapon with a reputation for toughness and reliability. The XM29 OICW, which combined both an assault rifle and a smart grenade launcher, turned out to be too heavy, fragile, and expensive. The rifle part of the XM29 was adapted to become the XM8. The smart grenade launcher part of the XM29 is being developed separately as the XM25.

xm8b.jpg The XM8 is a modular weapon that can be adapted to different roles fairly easily. It can use any of four barrel sizes: 9″, 12.5″, 20″, and heavy 20″.

The 9″ barrel makes the weapon a submachinegun-like personal defense weapon (called the Compact Carbine) that would be ideal for vehicle crews. Also, I imagine that Special Forces types would find it useful for urban raiding missions and the like. With the buttcap (as pictured on the right, second from the top) it is less than 21″ long overall.

The 12.5″ barrel is the standard set-up, and with the adjustable buttstock, makes the Baseline Carbine variant. With the stock fully extended, it is 33″ long, the same as an M4 (which has a 14.5″ barrel). It weighs in at about 6.4 lbs, with a goal of being reduced to 5.7 lbs. The M4 with comparable accessories weighs nearly 9 lbs. The pic at right shows an XM320 side-loading detachable grenade launcher mounted.

There are two versions of the 20″ barrel. There’s a standard weight match-grade unit for sharpshooter work and a heavy-duty machinegun unit with a folding bipod for use as a sustained fire automatic rifle.

The XM8 seems to be an aberration in the military procurement sector. It is a model that seems to improve upon its inspiration in terms of cost and weight, while sacrificing none of the qualities that made the original so good. An XM8 Baseline Carbine, with its integrated sight, will cost around $1800. An M4 equipped similarly costs over $2500. That translates into a savings of $2.4 million to equip a 3,500 man brigade.

Cost notwithstanding, the biggest advantage of the XM8 over the M4/M16 is almost certainly the new weapon’s durability and resistance to jamming. The manufacturer claims that the XM8 can fire over 15,000 rounds without lubrication or cleaning, even in harsh conditions. While I seriously doubt that those numbers would translate into the field, it is indicative of the weapon’s reliability. The BARREL LIFE of an M4 is rated at 8,000 rounds.

The XM8 achieves this phenomenal reliability in part due to a unique gas-operated pusher-rod operated bolt. This system does not send carbon gasses into the receiver with every round like standard weapons, and therefore reduces greatly the amount of propellant that could potentially foul the action or attract material that could. Additionally, the seal between the bolt and the ejection port is much tighter than in current weapons, which will limit the amount of crud that can get in that way. Also, the weapon can be fired even if the action is flooded with water. No draining required.

While I doubt any squad leader would ever allow anyone to go an extended period of time without cleaning their weapon, regardless of manufacturer’s ratings, there is a fair amount of time savings still to be found. First of all, the XM8 can be field cleaned in 4 minutes. This compares to more than 10 or 12 minutes for an M4, which translates into a an extra bit of rest, patrol, or other duties for the XM8-equipped soldier. Weapons are cleaned at least twice daily, if not more, so this 5-8 minute savings is not insignificant when multiplied by three thousand soldiers in a typical brigade. Also, the integrated sight is zeroed-in at the factory and does not require continual re-zeroing in the field by the troops.

Dirty and jammed weapons seem to have contributed to the defeat of the maintenance group that included Jessica Lynch during the invasion of Iraq. Part of the problem seems to be that the Army-supplied cleaning lubricant isn’t effective, especially against the fine Iraq sand. But non-combat units probably don’t devote enough time to cleaning and maintaining their weapons. The XM8 could help alleviate that by reducing the time required to complete the task, which will increase the odds that the task is attempted, and by being more forgiving if/when the task is forgotten or ignored.

Another nifty feature is the ability to be quickly adapted to fire AK-47 ammunition. This would be especially useful in Iraq, since there’s more AK-47 ammo in Iraq than there is sand.

For a comprehensive comparison of the XM8 Lightweight Modular Weapons System (LMWS) Baseline Carbine to the current M4, check out this .pdf. Keep in mind that it was published by the manufacturier of the XM8.

For an 18 second video of a full-auto firing of the XM8, check this out. HK-USA also has what amounts to a product brochure for the XM8 here. It includes drawings of many of the interchangable components of the XM8 system.

The XM8 has recently finished heavy testing. The next step is going to be to equip two full brgades with the weapons. I’ve been unable to learn which brigades get to be the lucky ones to try a new standard weapon out for the purposes of working out all the bugs. Maybe they haven’t been determined yet. I’d suggest that, in addition to the the big tests, some individuals or small units deployed in Iraq and Afghanistan get them. We must learn how these things really perform, and no amound of testing and simulation can teach as many lessons as a few minutes on a real live battlefield can.

For all the apparent good news surrounding the XM8, one basic issue remains the caliber of round our troops need to be firing at the bad guys. The XM8 will fire the NATO standard 5.56x45mm round, the same as the M4 and M16. There is a lot of grumbling among the troops that this round is insufficient, especially when fired from an M4’s shorter barrel. The standard XM8’s barrel is two inches shorter than the M4, so this issue will be even more pronounced.

This is a very controverisal subject, with feverent believers on both sides. Many who think that a larger round, like the 6.8mm or the good ol’ 7.62mm, is needed admit that the 5.56 might be sufficient if the type of ammunition was altered instead of the size. There have been many reports from Iraq, Afghanistan, and Somalia that the current round just doesn’t cut it. I don’t know enough to have an opinion on the matter, but it certainly seems that something needs to be done.

Airborne Combat Engineer had a post back in November about the XM8 and the ammuntion debate. He notes that we’ve already got so much refinement and investment in the current M16 and M4 that it seems like a waste to start over with a new weapon. He asks why the current weapons can’t just be up-gunned with the new 6.8mm uppers that will soon be hitting the market. That’s a very good question, and one that I hope our military seriously considers.

Back in August I thought the same thing. But, if the XM8 performs in the field like it’s performed in the tests, we might be better off in the long run if we make the change. The cost, reliability, and adaptability of the new weapon may outweigh our experience with the current one.

UPDATE: A Sliding stock for XM8 compact carbine PDW has been added to the mix. Pictures and more.


  1. i think H & K made the HK416 after the decline of the XM8, and this was like a version of the M4 but redesighned from the inside so that it didn’t need to be cleaned so often and made it a more reliable than the M4. and this would have been alot cheeper alternitive to a completly new weapon that was’nt quit as good enough improved over the M16 for the money. it looks like a bit of a midlife improvment program that seams to be happening alot these days. e.g with the SA 80 A2.

  2. First thing, I will admit that I have not researched all the balistics or different projects in the works like many of you here. What many of you seem to be doing is constantly repeating alot of what has been said all ready. The bottom line to all of it is simple. The size of the round is NOT the issue. All weapons will jam in the extreme conditions of the desert if not properly taken care of. You can site me statistics all day about the ballistic coefficients of each round and it doesn’t change one simple fact. If you don’t hit it you can’t kill it. I even remember one quote of the 7.62 being able to pass through several objects and still doing damage at impact or something similar to that. I have heard the same load of c@#p for years about a 30-30 being a good brush gun for deer hunting. There is no such thing as a good brush gun, or a rifle that can pass through many objects and still do damage. Any impact of any round will most likely (except for one in a million) alter its path of travel. Go to a Marine Corps rifle range and watch as the dozens of people in training consistantly hit the black of the torso size target at 500 yards. I personally tended to group 10 rounds inside 10-12 inches at that range with a standard issue M-16 in Okinawa where trust me the wind does have a bearing, ask any one who has shot there. I will give some bearing to the fact that this was not a combat situation, but the bottom line is quite simple. You can either hit or miss with any size caliber, the difference is in the marksmanship trainging and the nerves of being under fire. The better trained you are the more likely you are to hit your target even in combat. So let’s not worry about the size of the round, and maybe we should emphasize the importance to the military leaders of making sure our troops get plenty of range time.

  3. Has the 416 got any more advantages then just it has to be cleaned less or does it maybe have improved accuracy, or is lighter or more durable.

  4. the design looked slightly bigger the forearm looked bigger but im sure it is still pretty light and the M16 snd M4 are already pretty accurate so i think its only real better to the M4 was less cleaning

  5. Hey dude take it easy, people get side tracked by some more better information about guns. So next time dont go off, just ask your question again cause not many people look at the previous comments. CHILL MATE

  6. The HK 416 is making a big impression at Blackwater shoot-out and all the Def-Dept evaluators that observed the 416 firing hundreds of rounds then taken apart in front of the evaluator seeing the bolt and carrier is cool not hot, and the face is clean. Specops is using the hk416 in afghanistan also, they are snaping then up. Robb HK 416 links: http://www.botac.com/hk416system.html http://www.hkdefense.us/corporate/media/pdf/416revised4-5-05.pdf http://www.hkdefense.us/corporate/media/pdf/JanesIDR416_Oct05.pdf http://www.armedforcesjournal.com/blackwater/real/HK416002.ram ****************************************

  7. we have talked about the xm8 in a while we should probably change name of room to meanigless all over the place Bullshit and of course the HK16

  8. The F2000 is bullpup, yet is ambidextrous, and can be fired from either shoulder. With the proper training, bullpup magazine changes are just as fast as with a conventional layout (just ask any British infantryman). Whether or not bullpups are uncomfortable is a matter of taste and of training. Bullpups are no heavier than conventional layouts; the FAMAS and Steyr AUG weigh the same as the M16A2, and the F2000 weighs less. Bullpups have been proven to work in combat many many times. The British, French, Austrian and Australian forces have all used bullpups in real combat situations with success. More and more countries are looking at adopting bullpup rifles. This includes Israel, Iran and China, all of whom have manufactured their own versions. The rumours of the British army considering the adoption of the G36 are completely unfounded … the new L85A2 has been proven (in tests and in battle) to be more reliable than the M16A2 and the G36. It has been officially stated that the A2 versions of the SA80 family will be kept until at least 2020, and is also being used as the main weapon in the UK’s Future Infantry Soldier Technology project. Australia and France are committed to bullpup rifles for the forseeable future as their bullpup rifles are being incorporated into their futuristic soldier projects.

  9. As I have stated previously in this forum, I completely agree with Doug97. The US should at least take a serious look at bullpups, either the F2000 or possibly a version of the SCAR with the working bits packaged into a bullpup envelope.

  10. looks the dogs, any side arm equive coming out any time soon also is the xm8 gonna be available for civilian purchase……….(legally)? thanks

  11. only thing i wanted to say is i’ve been using the M-16 series rifles for a while. as far as reliability is concerned the weapon system works well under stress so long as your willing to pay attention to the weapon system, i do agree the H&K firing assembly would be nice to reduce the carbon build up in the reciever. well deployed i’ve used the M-16A2, as well as the GAU and GUU models, and the last two deployments we’ve used the M-4’s, the weapon system is very touchy around sand and if left for more then a few days on your back with no attention. and as far as the 5.56 round not being effective at long ranges…..i’ve never shot at anything further then maybe 100 meters well deployed. usually most of the shots i made were less then 50 meters unless assigned to a precision engagement team, and in those situations we were usually carrying the M-24 while our spotter was armed with an M-4. the weapon wasn’t designed to be a sniper rifle, and we have weapons designed for making long range shots like that. our patrols allways carried some type of heavy weapon well capable of reaching out and touching someone. as far as this weapon not causing much damage to a human being? have you ever shot someone with it? i haven’t see someone get back up after taking a hit, honestly i think the weapon i would like to get replaced the most is our M-9 sidearms. we don’t use hollow points because of humanitarian reasons, and the 9X19mm nato round lacks punch, accuracy, and distance. honestly i’d replace that first, because i’d allmost go for the reload on my M-4 before going to the M-9, i’ve seen a full magazine not drop someone there. lets find a replacement thats going to make a huge difference, rather then a minor one. though on a good note, i do like the seeming versatility on the XM-8 and am very curious as to whether modifications to barrel length and stock would be easy enough for one soldier to carry the parts and be capable of converting it on his own. the M-4 just has 4 settings on the collapsible stock and thats all the diversity it comes with that can be performed in the field. if the barrel on the XM-8 can be detached seperately and replaced in the field i would be all for it, otherwise to get that versatility you’d have to carry multiple uppers with you.

  12. I completely agree with you on the pistol issue. But I think we should swich back to the colt.45, now that gun can take someone down with one shot.

  13. .45 ACP hardball is no more effective than standard 9mm 115 grain or 124 grain hardball. The much vaunted superiorety of the 45 ACP is based on speculation, conjecture and, especially, wishful thinking. If the US is indeed contemplating a return to a 45 ACP handgun, it should adopt a gun rated for the 45 Super cartridge. This would enable those who can handle it to use the 45 Super round with a 200 grain FMJ SWC at 1300 feet per second and those who do not want or need this powerful, hard recoiling cartridge, can still use the standard 230 grain hardball round. It should be noted however that, when the performance of its infantry weapons was evaluated by the US army after the second world war, a frequent complaint heard about the 45 ACP mod. 1911 pistols was that of excessive recoil! If the troops complain about the recoil of the standard 45 ACP round, the 45 Super will scare the bejeeses out of them!

  14. ok, so why don’t they make a .45 pistol with similiar recoil reducing mechanics as the M107?. It’d be better than havin that wussy 9mm.

  15. we don’t use hollow points because of humanitarian reasons’ Who gives a rat’s arse about ‘humanitarian’ reasons, when those Iraqi bast*rds are torturing and beheading captured American soldiers???? Why do we always try to wear the ‘white hat’ when in combat, and the other side uses that against us? Personally, you have MY persmission as an American Taxpayer, to use what EVER ammo you need to put the enemy down before he can harm you! This is not a paintball game, or a video game that you can reset, this is AMERICAN LIVES at stake! Not to mention our fellow allies the Brits, Aussies, and Canuks! (and THANK YOU for being there for us!!!! It IS appreciated!!!). As for the M16, I was almost drafted back in the 70’s, but it ended before they got to me. I so remember all the TV reports about the early M16 jamming all the time in Nam. I wish they had kept the M14 – that had reliability and stopping power – as well as great range. I had seen a demo at a Civil War re-enactment, where they had experts shot the old CW muskets, sharps carbine, M16, and the M14. Believe it or not, some of those re-enactors could out shoot the mil guys with he modern weapons! But when they showed how the M14 could rip apart concrete blocks, THAT was amazing! And considering what the building materials are in some Iraqi shacks, that is what is needed to root out those murdering scum. So though the XM8 has a cool look to it, looks won’t stop the enemy. Wish it had the 7.62 ammo for it. Then it might have been perfect. Oh, and by the way – if you want an XM8 replica that you could at least shoot, there are 2 paintball models made now. The SP-8 from Smart Parts (with both the stubby and the long barrel models), and the MKX8 from Blackpoint Engineering (also known as JCS) that is a more realistic version that scenario players seem to love.

  16. HarryKrishna wrote: ‘I wish they had kept the M14 – that had reliability and stopping power – as well as great range.’ Wish no more ~ The M14 is currently kicking Islamic Terrorist Ass in Iraq and Afghanistan. Smith Enterprise, Inc. is building enhanced, modernized M14 battle rifles for our military. Check out the Crazy Horse M-14SE (SASS) and the MK14 MOD 0 EBR SEI.

  17. Has anybody heard anything else about the XM8? I heard that the development went on hold. Is in our soldiers’ hands yet or still being tested? I have personally tested it on Ghost Recon 3, great game ;), It its pretty cool. The new side loading grenade launcher looks cool, i wonder if you can shoot it while its off your rifle. The only thing that needs a bigger caliber are the pistols of the army. Now all the pistols have switched to 9 mm ammo. There is no point to have to shoot half your clip at someone and then watched them get up and run away when u could shoot one or two bullets and out them down for good. What they should do is upgrade the colt .45, which has not been upgraded in almost 100 years. But if anybody has any information about the whereabouts of the XM8, if has been changed to the M8 or not, please respond. Alex, age 14

  18. This is the only informational video i have found about the XM8 on the internet, but it is old and was made before the development was put on hold. http://www.armytimes.com/story.php?s=1-292925-xm8.php

  19. this is skyler asking about the xm-8 please respond if anyone hears about anything or email me at

  20. Im a army vet, I built a few 45 acps and thay turned out paper punchers also I built 2 ar/15 1 w/16 bbl and 1 w/20 bbl and they both are great shooters, I do not understand why we cant use special ammo, as those dam terrost kill our people and we have to use a ball round, dam it use a hollow point with a small explosive charge init, and in the hand guns also this will make the small 5,56 into a ausom killing machine.and the 9mm will take of a limb with that ammo why must we kill with a round that id==s not so bad, dam it they kill us so why dont we use spl. ammo with a small warhead in it.a 5.56 will be like a 12 gauge with a small charge in its tip. come on people wake up it is our own people that are getting killed over there for our freedom, so lets give them a hand.arm them with the best that we can give them,

  21. You know, 9 out of 10 insurgents say that the current 5.56 rounds kill with one shot. I’ve never heard of a 5.56 with an explosive tip. That sounds like something out of a videogame. Sounds like a good idea, but the truth is, it would be pretty expensive. The Mk262 Mod 1 has been reported to have outstanding ballistics to 300 meters, a more devestaing wound at 2100 fps than the M855 at 2800 fps, and past that…well, it’s still not healthy to have an inch of copper and lead ripping through your chest. A lot of people advocate a JHP .223 for CT missions. The problem is, it would not fragment, it would just expand, and its penetration would not be enough reach the vital organs reliably. Anyway…about the XM8: Dead, dead and dead. The SCAR? Up in the air. With piston driven ARs coming on the scene, 2 expensive wars being fought, and a potentially more liberal congress, it’s anyone’s guess.

  22. Okay, what would be the pro’s and cons of adopting the 7.62×39 outside the SOF? Considering the glut of stockpiles of this round in former Soviet sattalites and supported states, the ease and quality at which US ammo producers have put forth said cartrage, and finally the fact the US and NATO forces seem to endlessly run into this round, seems to me that this may be worth considering for carbine weapons used by at least front-line infantry. The XM-8 may be dead, but the fack the H&K put forth the thought that a 7.62×39 conversion be offered may show that the NATO world of arms production may be more open to the old russian round than they were during the Cold War. The only arguments against the round I’ve heard were range and penatration. Though it seems that those arguments seem to be moot as this tread has shown with complaints about the 5.56x45NATO being that these needs are not being run into in the field. I’ve also run into SLAP rounds in this caliber that have insane penatration and range nearly equal to the 5.56&45Nato. What are your thoughts?

  23. Just a thought, what if they made the XM8 a 7.62 weapon and issue out different bolt heads and a special gas-valve so the weapon can be quickly prepared to fire 7.62x39mm, 7.62NATO and 30-06. It’d give a soldier very good compatability, especially in the middle-east where there is more AK-47s than camels. What do you guys think??

  24. Pretty good information. The grenade launcher can be fired alone which is pretty interesting. The XM8 looks like a very good weapon. Changing the round to 7.62 rounds is a little strange as the US uses the 5.56 NATO as a standard rifle bullet.

  25. The comanche was a extremely pro attack helicopter. I had read it somewhere in a book. It had stealth capabilities and the weapon system like the F-22. (the folding out and in)

  26. Hey guys quick thought, IF I do recall this Xm-8 is fully modular from a 556 to a 762. So the ammo question is kind of moot considering you could just dump the 556 barrel (polygynal barrel or not its still shorter) and stick witht he 762 set up. But then again just a thought.

  27. pesonally i think that the xm8 wont fail in the feild cause it is much lighter than the regular m4 and m16 standard issue rifle but i would prefer to use the scar h rifle with its heavy hitting nato round

  28. As a Marine infrantry man who did my time in Iraq I have to admitt I liked my M4. It was great in the houses I cleared, but as I found myself shooting at targets over 300 meters away the round had a less than desirable affect on two of my targets. I don’t care if the XM8 makes it to the fleet the only thing I would really like to see in our military is the new 6.8 round. I never liked the idea of shoot to hurt. I’d rather have one man dead than two kind of hurt. I’d still really like to own a XM8.