The M41A1 “Pulse Rifle” with attached M352A2 underbarrel shotgun (identifiable from the M339 underbarrel grenade launcher by its slightly smaller size and lack of leaf sight on top of the carrying handle) and muzzle thread protector. Also note that this weapon is missing its emergency ejection port cover.

The M41 submachine gun was a trend-setting weapon designed by retired United States Marine Corps Colonel Jonathon LaForce in 2027. Unlike most firearms, it not only utilizes caseless ammunition but also an electronic ignition system instead of being hammer- or striker-fired.

In an era where the submachine gun was rapidly falling out of general use due to the rise of the Personal Defense Weapon class of firearms and their relatively high-powered cartridges equipped with bottlenecked casings and low-caliber spitzer bullets, LaForce’s design gave the submachine concept new life, largely due to the fact that the ammunition he designed for the M41 could contain explosives, while the smaller-diameter rounds used by PDWs could not carry enough explosive to make them equally effective. LaForce’s “ground-up” approach to both the new cartridge and the gun itself also helped the weapon avoid some of the other traditional shortcomings of submachine guns, like a low effective range; while most submachine guns have a maximum effective range of 100-150 meters, the M41 has a maximum effective range of 250 meters, comparable to the P90 and other PDW-class firearms.

The M41 was adopted by the US military in 2028 and was initially used as their primary compact weapon, replacing the M4 carbine and M27 Infantry Automatic Rifle in select non-infantry roles, as well as units fighting in certain urban environments or on space stations or ships, as features like its caseless explosive ammunition make it particularly useful for those types of combat. However, some of those same advantages also limit its use as the caseless ammunition is rather sensitive to outside contaminants.

Two years after the M41 was adopted, it was replaced by the improved M41A1; existing M41s could be converted to M41A1 standard simply by replacing certain parts. It was later largely replaced by the M39 submachine gun but remained in service in specialist roles for over 150 years.

Weapon Designation:Submachine Gun, 10mm, Caseless, Pulse-Fired, M41
Submachine Gun, 10mm, Caseless, Pulse-Fired, M41A1
Type:Submachine Gun
Place of OriginUnited States
In Service:2027-2030 (M41)
2030-present (M41A1)
Production History:
Manufacturer:Armat Battlefield Systems
Produced:2028-2030 (M41)
2030-present (M41A1)
Weight:6.38 lb (2.9 kg) (M41/M41A1, empty, without underbarrel attachments)
Length:33 in (840 mm) (M41)
33 in (840 mm) (stock open) (M41A1)
27.36 in (695 mm) (stock closed) (M41A1)
Barrel Length:9.72 in (247 mm)
Cartridge:10x24mm Caseless
Action:Roller-delayed blowback, electronically ignited cartridges
Rate of Fire:900 rounds/min cyclic
Muzzle Velocity:1,663 ft/s (507 m/s)
Muzzle Energy:1,290 ft/lbs (1,749 Joules)
Effective Range:250 m (273 yd)
Feed System:40-round detachable box magazine
Sights:Iron sights, M76A1 CQO red dot sight, SE-1 thermal/laser sight


Jonathan LaForce was a retired USMC Colonel who began work on the M41 in 2026, incorporating his combat experiences during his service. In late 2026, the Department of Defense became aware of his design and was so interested that not only did they encourage him to continue developing it, but even borrowed concepts from the weapon for a full-sized service rifle utilizing caseless, electronically-fired ammunition, commissioning Armat Battlefield Systems to develop the weapon alongside LaForce’s endeavor. However, the rifle, known as the XM37, proved to have only mediocre reliability and the fragility and susceptibility to contamination of the caseless ammunition led to the rifle being considered unacceptable for the harsh environments in which it would be used. Although the DOD lost interest in the XM37 and the concept of a standard-issue rifle firing caseless ammunition, they did express continued interest in the XM41 because of a perceived ability to deploy it in more controlled environments where ammunition contamination was less likely and also because of the potential of the explosive rounds it fired, which were also designed by LaForce.

In late 2027, LaForce completed his design and it was trialed and accepted by the United States as the M41 submachine gun. Although their XM37 had been rejected, Armat Battlefield Systems quickly purchased a production license for the M41, resulting in LaForce receiving sizeable royalty payments for the rest of his life. Armat began full production of the M41 in early 2028.

The introduction of the M41 and its explosive ammunition caused an international stir. In the late 2020s, many nations continued to observe the Saint Petersburg Declaration of 1868, which banned the use of explosive projectiles that weighed less than 400 grams. However, the United States was not a signatory of the Saint Petersburg Declaration and therefore not restricted by it. Despite the international reaction, the US continued to issue the explosive ammunition. In 2030, when the improved M41A1 pulse rifle came out and was adopted by Japan and Germany, and when the German MG56, which used the same ammunition, came out the year after, the concept became better accepted.

Despite some limitations, the M41 quickly built a reputation for being a reliable, effective weapon, and with the passage of the Future Weapons Development Ban in 2036, weapons technology development became drastically limited to the point that it was virtually impossible to design a more technologically-advanced firearm and so the M41’s improved variant, the M41A1, was planned to remain the military’s primary submachine gun for the foreseeable future. Ironically, the Future Weapons Development Ban explicitly stated that all previous international agreements regarding weapon bans were considered nullified in favor of the FWDB’s legislation. This meant that the Saint Petersburg Declaration as well as portions of the 1899 and 1907 Hague Conventions were no longer in effect and despite the previous controversy, the FWDB did not ban the use of small explosive projectiles. Although never explicitly stated by any country, a number of political analysts theorized that this was due to several countries wishing either to adopt the M41 or MG56 or to pursue similar designs of their own due to their effectiveness.

By the late 2040s, however, some further drawbacks to the M41’s design were beginning to show. Although not an excessively heavy weapon and considered of a reasonable size for its firepower, many troops did consider it to be larger and heavier than ideal, as well as having higher recoil than most other weapons of a similar type. Tank crews were particularly unhappy with its size, although they praised its firepower. As a result, a compromise was reached. A new submachine gun firing explosive ammunition would be developed to largely replace the M41, while the M41 would be retained as limited-standard for certain users. The result of this program was the Heckler and Koch M39 submachine gun, based on their UMP design. Out of the five branches of the US military, the M41 was most heavily used by the Navy, and was in fact the most common long arm the Navy employed due to its suitability for use in ship security, boarding missions, and special operations, even after the adoption of the M39. It was particularly prized by Navy SEALs.


The M41 uses an unconventional “double-layer” body. The main receiver is made of aluminum for light weight, while the outer shell is made of a heat-resistant polymer to protect the operator from the high temperatures often generated by firing. Because the top of the receiver is exposed to aid cooling, the large carry handle also serves to protect the operator from accidentally touching the hot metal surface. The M41 is a compact weapon, measuring only 33 inches long. This makes it comparable to the M933P carbine in terms of length, although it weighs almost two pounds more and the roles filled by the two weapons are rather different. It has a distinctive forward handguard with eight vent slots cut in each side and a long cut-out along the top, and the bottom of the handguard can be removed to accomodate the M339 underbarrel grenade launcher or M352 underbarrel shotgun.

In addition to its electronic firing mechanism, the M41 features an ammunition counter display on the right side of the magazine well. It can be dimmed for operations in dark areas or shut off completely. Both it and the firing mechanism are powered by a battery installed in the gun’s pistol grip.

The M41 features a charging handle on the right side, used for chambering a round when a new magazine is inserted with the chamber empty and also for ejecting failed or training-use rounds. Although LaForce’s decision to only put the charging handle on one side was somewhat controversial because it was not considered ambidextrous, LaForce himself demonstrated during trials that a right-handed user could easily slip their left hand under the carry handle and over the receiver to reach the handle, while a left-handed user could reach the handle directly with their right hand. An ejection port cover is installed over the emergency ejection port and will pop open when struck by an unfired round being ejected. This helps seal the weapon from foreign debris, aiding reliability, although once the port opens to allow a round to be ejected, it must be manually pushed closed.


The M41 fires caseless ammunition, which comes with several unique advantages and disadvantages. Although the removal of the extraction and ejection phases of the firing cycle improve reliability and the caseless ammunition weighs less per round than an equivalent cased cartridge, the caseless rounds are both fragile and susceptible to contamination by any liquid they might come in contact with, including water, left-over cleaning solvent, and potentially even excessive lubrication. Conversely, the lack of an ejection phase in the operating cycle makes the gun an almost completely sealed system, which minimizes the entry of foreign debris. This in itself provides some protection from water but much more importantly provides almost complete protection from sand or other small debris that could otherwise enter and jam the weapon. This means that the M41 has exceptional reliability when used in sandy or dusty environments, which is why even after the adoption of the M39, the M41 continues to see use with certain regular infantry units who frequently operate in such areas.

In a firearm firing cased ammunition, each spent casing acts as a heat sink, carrying a significant amount of heat away from the weapon, while in a firearm that uses caseless ammunition that heat remains in the weapon and continues to build up, leading to overheating and even ammunition cook-off. Because of this, the M41 is somewhat unsuited for periods of sustained fire, although the polymer outer casing helps protect the operator from the receiver itself when it grows hot.

Despite its weaknesses, the M10-210 round is also highly effective. Fired from the M41’s 9.72 inch barrel, with a rifling twist rate of 1:16, the 210-grain round reaches a muzzle velocity of 1,663 feet per second, and a muzzle energy of 1,290 ft/lbs. This is further augmented by the use of an explosive filler that makes up most of the bullet’s mass. The explosive material used, LIRE, or Limited Impact Resistance Explosive, is impact sensitive so that a fusing system is not required for each individual round, but stable enough that the force required to detonate the bullet can only be generated by an impact while in flight; thus, the ammunition cannot be unintentionally detonated by dropping a round, magazine, or loaded gun. However, there was at least one recorded instance where an airdropped pallet containing LIRE ammunition suffered a parachute malfunction and exploded on impact with the ground. This resulted in certain restrictions placed on the airdropping of LIRE ammunition.

Because the M41’s ammunition makes it unsuitable for use in certain harsh environments, the similarly-sized M933P carbine and the smaller M39 are more frequently used, although in places like space stations and ships where the weapon and its ammunition are less likely to come into contact with sources of contamination, the M41’s explosive rounds give it a significant advantage in firepower over the smaller explosive rounds of the M39 and the M933P’s metal-only rounds. The M41 has better range than the M39 but slightly less than the M933P, while in sandy or dusty environments its reliability stands well above both weapons.


The M41’s carrying handle has a deep groove running down the center of it which accommodates both the front and rear sights; while the front sight is a simple post, the rear sight is a “V” notch sighted at one hundred meters with a secondary flip-up notch zeroed for two hundred meters very similar to the MP40 submachine gun’s sight. Additionally, the M41 has a hole cut in the center of its sight groove; the hole and groove together are used to mount and secure the M76A1 Close Quarters Optic red dot sight, a modification of the M76 red dot sight that is mounted in a very similar fashion to the Colt 4x20mm handle-mounted scope used on the M16A5P. This “hole and groove” mount is also used to mount the leaf sight for the M339 underbarrel grenade launcher.


The M41 is fed from a forty-round double-stack double-feed box magazine. Several experimental designs with higher capacities were attempted, including one highly unconventional U-shaped design that carried ninety-nine rounds. This design failed because it was considered to be too long, too wide, and excessively heavy, as well as having miserable reliability due to issues with the square ammunition turning the 180-degree curve at the bottom of the magazine. The weight distribution of the wide magazine was even bad enough to unbalance the entire weapon. The forty-round magazine has remained the only magazine accepted by the US military for use with the M41.

Additional Accessories:

Although promotional and recruiting posters, particularly for the Colonial Marines, frequently depict M41s with the M339 underbarrel grenade launcher mounted, this weapon is only issued to infantry grenadiers and fireteam leaders in certain Special Forces units. It provides an important boost in firepower but the extra weight of both the launcher and the grenades as well as the resulting lower number of magazines for the gun itself that a user can carry mean that it is not practical for every Marine who uses an M41 to have a grenade launcher fitted to it.

The M41 can also be fitted with the M352A2 underbarrel shotgun, a pump-action shotgun which holds two rounds in the magazine and a third in the chamber. And while the M41 cannot directly mount a bayonet to the barrel with a conventional bayonet lug system, a third option is a bayonet that slides onto the mount rail for the M339 and M352A2, with a ring mount long enough to fit over the flash hider.


The M41A1 is an improved version of the M41 that entered service in 2030. The most obvious difference is the replacement of the M41’s fixed stock with a collapsible stock that can shorten the weapon’s length to just 27.36 inches. The M41A1 also replaced the M41’s outer casing with an improved casing that features a combination thermal/laser sight installed in its prominent carry handle just ahead of the emergency ejection port. This sight, designated the Sight, Electronic 1, or SE-1, is based on the technology of the BAE Systems “Family of Weapon Sights-Individual” sight and is capable of transmitting images to the user’s M10 helmet computer and display systems, allowing them to see where the weapon is being aimed even in complete darkness, and additionally offering the ability to fire the weapon around corners whiile the operator remains under cover.

The M41’s rear iron sight was also updated and replaced with a peep sight very similar to that of the rear sight used by the M1 Carbine, with a sliding ramp used to adjust for elevation at fifty, one hundred, one hundred fifty, and two hundred meters. The sight is windage adjustable by a small dial underneath the ramp assembly that moves the entire sight to the right or left. Lastly, the M41A1 has a threaded barrel for the attachment of a suppressor or various flash hiders, compensators, or muzzle brakes depending on the user’s preference or mission requirements.

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