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.

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.