Following up on their previous interview segments with AR-15 designer Jim Sullivan, Forgotten Weapons and InRange have posted a video on Full30 of Sullivan describing his view of what went wrong with the AR-15 in Vietnam. Sullivan’s view essentially boils down to “they changed the type of powder that was used, which raised the port pressure, causing the gun to run faster and which led to malfunctions”. This is essentially true, but to help add more depth and clarity to the matter, I asked Daniel Watters, author of The Gun Zone’s 5.56mm Timeline, to give a summary in his words of the AR-15’s propellant woes. Watters has already written about the matter, but elaborated further in our conversation, so that I could share it with our readers:
From his description in the video, Mr. Sullivan is repeating what was reported elsewhere such as the Ichord Subcommittee report, and the propellant issue was far more complicated than the popular narrative supported by the Ichord Subcommittee. More than a fair amount of mythology has been built up about the DuPont Improved Military Powder (IMR), and I suspect IMR 4475 would have to posed its own problems in Vietnam if DuPont had not withdrawn it as a qualified propellant for M193. It certainly would not have solved the problems with chamber corrosion or non-existent case hardness standards.
You have to remember that the Office of Secretary of Defense (OSD) saw the procurement of the AR-15 and its .223 ammunition as a Commercial Off The Shelf purchase. The expectation was that little tweaking would be necessary to field it successfully, and that the Army could simply adopt the commercial specifications for the rifle and ammunition as-is for their own Mil-Specs. For instance, the military’s original velocity and pressure specifications for 5.56mm M193 were based on Remington’s commercial specifications for .223. However, while the average civilian user of the .223 would have no way to tell if Remington had fudged their figures, the military did, and took Remington to task. All of the hype about the effectiveness of the rifle and cartridge was tied to its high velocity, and thus, a reduction of velocity could easily be seen as reducing its effectiveness. As the prime user of the rifle in 1963 when all of this was hashed out, the USAF was unwilling to accept a loss in range by relaxing the velocity specifications. (The same thing had occurred earlier when the USAF discovered that the bullet was unstable in cold weather with the 1-14″ rifling twist. The USAF testers suggested that the stability problem could probably be solved if the bullet was simply shortened by going to a flat-base design of the same weight, but the change in shape would reduce long range performance.)
However, the refusal to budge from the velocity standards led to an additional complication when it was discovered that IMR 4475-loaded ammunition could not met these specifications while consistently maintaining the proper tolerances for chamber pressure. Previously, Remington could simply cherry-pick lots of IMR 4475, but but this would no longer be possible once M193 reached mass production. Some have asked why the chamber pressure specifications were such a problem, and why not simply increase the chamber pressure specifications so IMR 4475 could be kept. The problem was that the military evaluations in late 1962-early 1963 had already shown signs of pressure excursions like popped primers. Some of the over-pressure events during were probably the result of Remington and Colt not comparing notes on Remington’s changes in ammunition and chamber dimensions when they established SAAMI specifications for the .223. It appears that Colt’s chambers at the time were smaller than the final SAAMI specs for commercial .223, which is even smaller than what we now have as standard for 5.56mm. Increasing chamber dimensions partially helped moderate the pressure issue, but then likely resulted in a reduction in velocity.
The first clue that the pressure/velocity specifications were going to pose a problem was when all of the major commercial ammunition manufacturers balked on bidding for M193 production contracts as long as the existing specifications remained in place. With no one willing to budge on pressure or velocity, the only other possibility was the propellant. The first to suggest a change of propellant from IMR 4475 was Remington themselves, in order to fulfill an existing USAF ammunition contract. Ironically, Remington proposed alternative was Olin’s WC846. (Mind you, Remington was owned by DuPont, the manufacturers of IMR brand powders.)
A search for alternate M193 propellants was underway when Remington and DuPont withdrew IMR 4475 as a qualified propellant in March 1964. WC846 and IMR CR8136 were approved by the Army for M193 in April 1964. At that time, only Remington chose to load M193 with CR8136. Winchester and Federal went with WC846. By the end of 1964, Remington dropped CR8136, again due to lot-to-lot consistency issues. So this set off another search for alternative propellants, and IMR 8208M was approved for use in M193. This time, all of the commercial manufacturers, including Remington, went with WC846. As a result, Lake City and Twin Cities ended up loading M193 with IMR 8208M. IMR 8208M was not dropped from use with M193 until after the WSEG testing in 1968. The mere fact that other propellants, including IMR-types, were approved for M193 should put to rest the old myth that IMR 4475 was rejected so the Army could sole-source Olin Ball Powders like WC846. IMR 8208M had in fact been the off-shoot of another propellant developed by DuPont under Army contract for 7.62mm NATO. The 7.62mm propellant had to be modified as its grains were too long for automated loading given the 5.56mm’s narrower case neck.
The stories that WC846 was never tested or that Colt did not know or approve of the change are also false. Colt had USAF ammo loaded with WC846 in early 1964, and pointed out the increase in cyclic rates in March. Colt went even further and had tests done at H.P. White to determine the cause of the cyclic rate increase. In April 1964, Colt’s senior product engineer Foster Sturtevant wrote in an internal report that the higher gas port pressures with WC846 were “in no way harmful to the AR-15” and would lead to more positive functioning of the rifle. It strikes me that the increased cyclic rate was initially tolerated because some uninformed souls saw it as a bonus feature, not a flaw. After all, the USAF’s aircraft armaments were designed around even higher cyclic rates. Imagine trying to argue in favor of revising the velocity specs of M193, when Remington and Colt have already signed off on a change in propellant. As for the claim that the propellants were not tested for port pressure, Colt simply didn’t know what the appropriate port pressure should be, and the OSD’s pressure to get the rifles fielded meant that no one wanted to wait to run tests to find out what the acceptable limits should be. William C. Davis, Jr. and his colleagues at Frankford Arsenal basically had to guess.
Another myth is the idea that the military should have kept IMR 4475 despite its issues since it was part of the .223 design since the beginning. A curious point to come out of the Ichord Hearings was multiple mentions that Remington had not always used IMR 4475 for the early .223. Yount mentioned that some test ammunition had been loaded with IMR 4198, and one of the USAF witnesses claimed that they had IMR 4064 in the USAF’s initial 1963 specs until they contacted Remington as to their preferred powder and primer. Most damning was the DuPont witness who testified that Remington adopted IMR 4475 for the .223 as late as 1962. I find it particularly odd that Ichord never subpoenaed representatives from Remington, Olin, Federal, or Hercules.
A seemingly unkillable narrative is that IMR was a new improved design sabotaged by traditionalists unwilling to give up outdated surplus propellants or offend a powerful vendor like Olin. First, the name “Improved Military Rifle” was merely a brand name. It signified the change from DuPont’s earlier “Military Rifle”-brand extruded powders, which used straight nitrocellulose to IMR’s deterrent coated nitrocellulose. IMR propellant types are actually older than Olin’s Ball Powder types. The specific type used, IMR 4475, was actually introduced back in the 1930s. To somehow suggest that DuPont was not a full-fledged, card-carrying member of the Military/Industrial Complex and had any less of a cozy relationship than Olin is patently ridiculous.
Was there a wide-spread conspiracy to kill the M16? Certainly the Army General Staff wanted little to do with the rifle, and were hoping that they could either restart M14 production or wait until the SPIW or another alternative was available. However, the Army Materiel Command’s General Frank Besson took very close interest in Project Manager Colonel Yount’s progress. Besson routinely marked up his copy of Yount’s weekly significant action reports and sent it back for further comment. Moreover, some of the folks on the M16’s Technical Coordinating Committee, like Frankford Arsenal’s Bill Davis, appeared to be selected specifically because of their previous SCHV work. One of the biggest impediments to the rifle’s development seem to have been the Secretary of Defense and his staff. They had drunk the Kool-Aid that the AR-15 and its ammo were a fully developed, perfectly perfect, Commercial Off the Shelf product that needed no additional work prior to issue. They wanted the rifle issued, and they wanted it done NOW.
Some of the problems in Vietnam were going to happen regardless of which powder type was used. Case hardness standards were left up to the individual manufacturer, who likely used the same case hardness specs that would be appropriate for hunting or target ammunition in a single shot or bolt action, but not for military ammo for an automatic weapon. The M16’s unchromed chambers were doomed to rust in a tropical environment, particularly given the widespread belief that the rifle needed little to no cleaning. Combine corroded chambers with soft brass, and you get failures to extract. As for the original action spring guide (buffer), its Edgewater springs had a tendency to seize when wet. When this happened, all buffering value was lost.
The early troop issues were to Special Forces and Airborne units, many of whom had a chance to train with their rifles prior to deployment to Vietnam. (Incidentally, despite what Mr. Sullivan claims, the 7th Cav would have used Colt XM16E1 at Ia Drang, not the 601 or 602, and certainly not original ArmaLite production.) By 1966, regular Infantry units were receiving them, many making the transition in country.
Rust doesn’t take long to start in humid climates if you aren’t taking care of it. One archive item, a 12/3/67 article from the Baltimore Sun stated that from one USMC battalion, 286 of 445 rifles inspected were going to need their barrels replaced due to corrosion in the chamber. It also claims that when they were issued their new rifles in the Spring, Marines were told not to oil their weapons after cleaning. This order was not rescinded until June.
Ordnance’s desire for chromed bores in all small arms tracked back to its experience in the Pacific during the Second World War. In his book “Ordnance Went Up Front,” Roy Dunlap indicated that when he served in the Pacific during WW2, he saw plenty of rifles that were turned in to Ordnance teams due to rusted bores. In one of the official Ordnance Department histories of WW2, there were comments that many rifles were wrecked in the Papua New Guinea campaign. Green US troops had tossed away their cleaning kits and oil bottles to save weight during their long march through the jungle. Once they finally made contact with the enemy, problems arose with their weapons due to the lack of maintenance. These troops were then forced to scrounge cleaning materiel from the corpses of Japanese troops killed in battle.
The M16’s issues also seem to track with growing pains related to dramatic increases in production rates. For instance, Colt continuously applied for cyclic rate waivers in 1964. They initially admitted that they had previously cherry picked rifles for submission, but could no longer continue this practice as the delivery schedule increased. There is a fair amount of anecdotal evidence that there were attempts to subvert the rifle inspection process. Again, there is a historical precedent. In May 1967, John Garand was interviewed about the problems the M16 was having in Vietnam. He noted that the M1 had also had problems in early combat. Production quotas had been ramped up so quickly that Springfield was forced to use parts that would have otherwise been rejected. He was quoted as saying “I questioned this and was told that it was better to have a gun jammed once in awhile than to have no gun at all. The answer shocked me.”
Sullivan certainly has right to be concerned about what happened to his rifle design once it was handed off; the journey of the AR-15 from limited production gun to standard Army rifle was reckless and fraught with both negligence and technical issues.
However, Watters’ description provides a little more insight. The Army didn’t switch the powders, nor did they insist on only using ball propellants.. All powder manufacturers had serious issues meeting the specifications in large production runs, including DuPont’s IMR 4475 (which worked great in small, controlled lots, but was unsuited to large-scale mass production within the standards set for 5.56mm ammunition). Powder, too, wasn’t the only problem; the case specifications and lack of chrome-lining and cleaning tools also seriously impacted the weapons’ reliability in theater.
Further information on the propellant issues of the early M16 rifle can be found in Appendix 4 of The Rifle Review Panel, Volume 5.
Special thanks to Daniel Watters for his assistance with this article.