This article is an excerpt from the Gun Digest Book of Classic Combat Rifles.
He explained the last thing you want to do is force a round into a dirty chamber, which quickly leads to function failures. The chamber fouling tends to embed in the soft brass cartridge case and lock it in, causing a fired cartridge case to be — literally — locked into the chamber at the moment of extraction.
Gene Stoner was able to prove the rifle and ammunition combination he furnished to Armalite/Colt was a totally reliable weapon system and the change the military made, without his consent, caused the malfunctions. He told the committee he expressed these concerns to the OSD Comptrollers office and was ignored. The subcommittee accepted this as the reason for the condition.
M16 rifle project manager, Col. Yout, was of particular interest to the subcommittee. Throughout the hearing he was accused of making irresponsible decisions as to the direction of the program.
Mr. Ichord [to Col. Yout]: “We have evidence and are advised by our experts … that Ball propellant, which you apparently speak so highly of, does have an adverse affect upon the operation of the M16 rifle. It speeded up the cyclic rate. It is dirtier burning … . When we are also advised that the Army was cautioned against making this change from IMR to Ball propellant … Naturally, we would be quite concerned. Apparently you aren’t so concerned. I don’t understand your explanation. I just haven’t been able to understand you — but perhaps you haven’t offered the information in words I can understand. Would you care to say something?” He never replied to the question.
The Army made a statement on July 27, 1967: “From the vantage point of retrospect, it has sometimes been suggested that the particular behavior of Ball propellant should have been predicted … Had the Army anticipated these developments, it is most unlikely that the course chosen in January, 1964, would have been the same. A decision to reduce the velocity requirement, and continue loading IMR4475 propellant would probably have been made instead, and development of alternate propellants could have been pursued more deliberately.”
This is the closest to an admission of negligence by the Army for the decision to use Ball powder. Gene Stoner warned them long before it got to this point; who would know more about the rifle’s performance and design intent than the man who designed it? In the end, the rifle was not the problem; instead, this was an ammunition-driven problem that altered the design intent of the rifle.
In August 1967, the hearings ended, and in October 1967, the subcommittee concluded, “Grave mismanagement, errors of judgment and lack of responsibility had characterized the Army’s handling of the entire M16 program.” They stated the officials in the Department of the Army were aware of the adverse affect of Ball propellant on the cyclic rate of the M16 rifle as early as March 1964, yet continued to accept delivery of additional thousands of rifles that were not subjected to acceptance or endurance tests using Ball propellant.
All Colt endurance testing was done using IMR 4475. The subcommittee also concluded, “The failure on the part of officials with authority in the Army to cause action to be taken to correct the deficiencies of the 5.56mm ammunition borders on criminal negligence.”
The cyclic rate of the rifle was increased 10 to 15 percent (approximately 200 rounds per minute), resulting in higher stress on certain components caused by the higher velocity of the bolt carrier assembly. As a result, there were parts driven beyond their working parameters – as well as the bolt opening prematurely.
Many parts were changed to more stringent specifications to help deal with the higher pressure curve and harder impact. To solve the chamber corrosion and failure-to-extract issues, all future production rifle barrels would be chrome-lined. Even though chrome-lining barrels is a military specification, Ordinance failed to require this basic requirement on the AR-15/M16 rifle system.