History of the M118 Ammunition

In the late 1950’s the United States military adopted the M14 battle rifle and M60 machine gun as standard combat arms incorporating the 7.62x51mm NATO cartridge which was the newly adopted NATO round. At this particular point in time the US Military had fallen back into the cycle of disbanding official snipers among its combat forces as well as sniper training programs. Because of this the few sniper rifles that remained in the various arsenals were old M1C’s and M1D’s as well as a few of the sniper versions of the M1903 rifles. These were all chambered for the old US military standard 30-06 Springfield. When tensions rose in a small country in South East Asia called Vietnam and the US once again found itself in a shooting war, both the US Army and the USMC had to rush their sniper programs back into action, but they soon discovered that not only was their training lacking, but they also did not have any adequate equipment to issue their new sniper units. The USMC literally raided the armories of their bases around the world to get any suitable Winchester M70 with a heavy barrel that they could find. Combined with some of their old M1903’s they got along okay, but again, they were chambered in 30-06. The US Army did not have any better luck and they found their own snipers using old M1C’s and D’s, also chambered in .30-06. It was clear to both branches that something had to change, and change quickly.

The USMC decided they wanted to incorporate a bolt action rifle and performed a quick evaluation of what was immediately available on the commercial market that might work and in 1967 adopted the Remington model 700 combined with a Redfield 3-9x40mm accurange scope. This setup was known as the M40. The US Army was just a little bit later and went the route of the semi-auto rifle and took a modified National Match M-14 and converted it to a sniper rifle. The Army also topped their rifle with a redfield scope but with a unique mounting system (ART). This sniper weapon system was known as the XM21. In both cases the military felt it was prudent to adopt a cartridge that was a NATO standard and after some initial testing with the 5.56x45mm NATO they decided on the more capable 7.62x51mm NATO, in the case of the Army, the decision was made for them by adopting a military issued rifle, the M-14 from which to base their sniper rifle. The USMC adopted an all new rifle in the form of a fairly standard Remington M700 and could have selected a different cartridge if desired, but elected to stick with the NATO standard.

When the different branches were evaluating the various different rifle systems available and trying to determine which to adopt, they were also at the same time evaluating ammunition and trying to determine complimentary ammo to use. It was, and is, widely known that the rifle is only as good as the ammunition it is shooting. Luckily for them, when the 7.62x51mm NATO was adopted in the 1950’s the Office of the Chief or Ordnance had Frankford Arsenal begin work on developing a match grade version of the 7.62, designated the T265, to be used in 300-yard international matches. In 1961 and 1962 systematic testing was conducted at Ft. Benning Georgia using experimental M14 National Match rifles to determine the best load for velocity and accuracy, and by 1963 the load had been designated the XM118, with the X indicating experimental. Finally in 1964 the new National Match M14 was introduced along with the new ‘M118 Match Cartridge’.

The new M118 ammo used the same 173gr FMJBT (Full Metal Jacket Boat Tail) bullet that the .30-06 M72 Match ammo used. This bullet was manufactured by Lake City and was based on the 1956 International Match bullet. The bullet itself had a lead alloy core (90% lead, 10% antimony) with a gilding metal jacket comprised of 90% copper and 10% zinc. The boattail was a 9 degree taper and was .225″ long. The original specification weight was 173gr but as time progressed and the tooling wore out, that weight began to spread from 172 – 175gr. The claimed ballistic coefficient of the bullet is .494 which was very high for that time period.

The case on the M118 ammo was a match grade military case produced by Lake City and it originally utilized the percussion primer No. 43. The initial M118 loads used either 44 grains of WC 846 powder or 42 grains of IMR 4895. By 1970 Lake City had changed to exclusively use the IMR 4895 as it was easier to clean the residue from bores. The overall length of the cartridge was 2.83″ and the average velocity was 2550 fps, about 100 fps slower than the M72 .30-06 match load. The early M118 ammo was noted to be accurate with very few complaints and the ammo made a good compliment to both the M40 and M21 sniper rifles and proved quite effective in combat during the Vietnam conflict.

As time wore on the quality of the M118 Match ammunition began to deteriorate and in as early as 1972 the USMC actually began some performance testing and then prepared a formal report about the need to improve the accuracy and quality of the M118 ammo for combat sniping. As a result of this and other complaints from combat troops, Frankford Arsenal seriously looked into improving product performance by updating manufacturing equipment, but there was no improvement. In 1976 the military tried to also improve the performance by increasing the technical requirements of the round and again, there was no improvement. Unfortunately, it was during the 1970’s that several changes were made to manufacturing that had negative effects on the accuracy of the M118 ammunition. The two biggest changes was the change from match grade brass to standard combat grade brass, the same as used on standard M80 machine gun ammunition. The other change was the switch from the primer No. 43 to the same primer used in other 7.62 ammo, specifically the primer No. 34 and primer No. 36. These two changes had significant negative impacts on the performance of the ammo, and no amount of changes to specification or tooling would be able to help.

After the USA pulled out of Vietnam the USMC had made the commitment to continue their sniper program during peace time and they continued to improve their equipment. The US Army, on the other hand, had once again disbanded their sniper program at the cessation of hostilities and it was the marksmanship units that had to lead up the pursuit of better equipment for the Army. These various military types met at a symposium and agreed that something had to change and it was widely accepted that what was referred to as “Mexican Match” ammunition was a far better ammunition than M118 Match ammo. ‘Mexican Match’ was made by using military 7.62 brass and loading it with the Sierra 168gr Match King bullet. The name ‘Mexican Match’ reportedly came about because the first time this load was used was during the PanAm games in Mexico City. The accuracy improvement over the M118 Match ammo was remarkable, often shooting as much as 50% tighter groups. Because of these results a new load was developed called the M852. The design was simple, put the 168gr Sierra Match King bullet on the same M118 brass and powder. The M852 was adopted in the early 1980’s and was for match use only. Because the Sierra Match King (SMK) bullet had a hollowtip as a byproduct of production, it was not regarded at the time as being acceptable for combat use in terms of abiding by the Laws of Land Warfare. Since the M852 was the new match load for competition use, the M118 was redesignated the M118 ‘Special Ball’, or SB, and was the authorized ammo for combat use by snipers. Unfortunately, the performance of the M118 ammo had not improved as nothing had changed beyond the name. In the early 1990’s the M852 was approved for combat use but the wheels of progress were already turning on something new.

When I went through the US Army Sniper School at Ft. Benning, and during my years as a sniper after that, I only used the M118 SB ammunition and I can attest to the questionable quality. The main problem was the inconsistency of the ammo. There were times where we would shoot a 1.5″ group at 500 yards and then with a different lot shoot a 5″ group at 500 yards. Because of this we tended to try and search at the good lots, if possible, when ammo was issued. The M24’s we used were great rifles and they tended to shoot better than 1 MOA with M118, and that was more of a testament to the quality of the rifle than the ammo. When we would switch to commercial match ammo, sub .5 MOA was no problem with our M24’s. I will admit that by the time I enlisted, the M118 SB seemed to have stabilized compared to some of the earlier lots of SB back in the 80’s that would shoot as bad as 2 or 3 MOA. As mentioned earlier, the tooling being used by Lake City/Frankford Arsenal at this time appeared to have been well worn and tolerances were loose. Bullet weights ranged from 172-175gr, powder charges fluctuated giving wide spreads of muzzle velocity, and then combined with the non match brass and the machine gun ammo primers, and you had ‘Special Ball’ ammo that was not very special.

While the M852 was approved for combat use in the 90’s, the M118 SB still continued to be the standard issue ammo for snipers and while the 168gr SMK bullet was a vast improvement to the 173gr M118 projectile, it still had design defects. Sierra designed the 168gr SMK for 300 meter UIT competition and as such they did not focus on long range ballistics. The design incorporated a sharper 13 degree boat tail instead of the 9 degree taper that is found on the 173gr M118 projectile, as well as some other long range bullets, including the very first Match King bullet that sierra produced, the 180gr. The problem is that when the 168gr SMK drops into the transonic layer (1000-1400 fps) at about 700 yards in the 308, the airflow no longer follows the boat tail and separates, causing instability and accuracy and efficiency loss at those longer ranges. Because of this, the M852 performance suffered at long range and the hunt was on again for a better solution.

As is often the case for the development of snipers and sniping equipment for the US Military, the USMC lead the way and in 1993 they laid out their new design specifications for an improved 7.62x51mm NATO sniping cartridge dubbed the M118 Special Ball Long Range (LR). The USMC worked with Lake City on the design of the cartridge which included a new projectile design that they then sent over to Sierra. Sierra quickly was able to get some prototypes to the USMC of this new bullet, now known as the 175gr Match King, which incorporated a 9 degree boat tail like the M118/M72 bullet design. The design of the new load also designated an increase in velocity by 30 fps, up to 2580 fps.

Sometimes it is funny how bureaucracy works, but one of the hurdles the USMC had to overcome was the actual name of the cartridge. Initially it was proposed to give it an entirely new nomenclature but by doing that it would cause a complete type classification of the new load which would cost money and resources that the USMC did not have at the time. So the idea was proposed to just change the specifications for the M118 to include a new 1000 yard long range requirement with its accompanying name modification, so the M118 Special Ball Long Range ammo name was born.

The M118 Special Ball Long Range, more commonly known as M118LR, also went back to utilizing match cases and a press fit, not staked, primer No. 43. The powder used on the original M118LR was 44 grains of WC 750 and of course the 175gr Sierra Match King bullet is utilized.

The initial test ammo was received in 1996 with test results for long range accuracy being very favorable. While there were some early mix-ups in pressure measurements, in the end, all the pressure tests came back well under SAAMI specifications for the 7.62x51mm NATO cartridge. The M118LR has been in production now since about 1998 with good success and it has been utilized very effectively through the many conflicts during this century, but with that being said, there is always room for improvement.

The M118LR ammo has seen extensive use in combat and in most all of those cases it was utilized in desert environments where the temperature variations in a 24 hour period can be extreme. One of the faults with the M118LR quickly started to become apparent and that was its sensitivity to temperature change. All gun powders will burn at different rates depending on the temperature, which then affects the velocity of the bullet as it leaves the barrel. But some powders are more, or less, sensitive to the temperature changes. Some of the newer powders are especially resilient to temperature change and show just slight differences between the extremes. Another issue with the M118LR ammo that needed to be addressed was the excessive muzzle flash during low light shooting that was a concern for concealment as well as night vision use.

Not only were the above concerns an issue, but accuracy once again was starting to falter with the ammunition and new standards were desired for long range capability of the M118LR load. This time around it was the Navy Special Warfare Center that headed up the charge to develop a product improved version of the M118LR ammunition to address the temperature sensitively, muzzle flash, and accuracy complaints and it also needed to be able to function in the new crop of semi-auto sniper rifles being employed by the various armed forces. The NSWC tested 20 different powder combinations as well as 15 different projectiles during their testing. The specifications required that the standard deviation for velocity could not exceed 15 fps in order to minimize vertical spread due to velocity differences, and the accuracy of 10 round groups had to fall within a 7″ extreme spread at 600 yards and a 3.5″ extreme spread at 300 yards. It was also desired that the bullet still be supersonic (1000+ fps) at 1000 yards. All of that plus the performance had to be comparable from -25 degrees to +165 degrees Fahrenheit.

Once again the 175gr Sierra Match King was selected as the bullet choice as well as new powder. But this time a unique ammunition manufacturer would be selected to load the ammo based on their merits. The Federal Cartridge Company was awarded the contract and the ammunition was designated the M118 Special Ball Long Range Mk316 Mod 0. Like with the M118LR, the name was just modified to keep from having to go through full classification for the new ammunition. Federal designed a new match case based on their Gold Medal Match cases and used a modified extruded propellant. Unfortunately the details of which propellant and the charge weight are not widely known at this time. Federal also uses their Gold Medal Match primer for this load. Essentially it is a specialized commercial load adapted for the military specifications. Part of the requirements also included much higher quality control measures which are probably nothing more than what Federal currently does on their commercial Gold Medal Match manufacturing line. Initial accuracy tests on the early production lots have been excellent with accuracy coming in at about .5 MOA at both 300 and 600 yards.

Additionally, calcium carbonate was added to the powder which drastically reduced the muzzle flash of the new ammo. With the new powder, the velocity difference between 165 degrees and -25 degrees was a very impressive 21 fps, where as the older M118LR varied 227 fps. Needless to say, that was a drastic improvement as well.

The Mk316 ammo is in the process of replacing the original M118LR ammo but it is unknown how long a full replacement will take, not to mention that there is already a Mod 1 (and probably Mod 2) versions of the ammo already being worked on and prepared for production. The special operations forces are getting the latest developed equipment and a lot of the information can be hard to come by without being in the right channels and you can rest assured that continued development will happen with venerable M118.

The M118 ammo, in all its iterations, has served the US military snipers well for half a century and it appears that it will continue to do so. The name has gotten longer but the new life each new version breaths back into this war horse only goes to grow its capability and reputation. Stay tuned as I am sure this is not the last chapter.

To Be Continued…