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1/25/2018 7:38:29 AM
Posted: 3/15/2006 12:29:28 PM EST
Stoner intended the AR-15 to use ammunition loaded with stick (IMR) powder. You may remember that there was difficulty in loading 5.56 M193 with IMR to the velocity required to penetrate a steel pot at 500 yards and maintain chamber pressure.

Then in 1968 the use of stick powder was suspended in the loading of M193.

So been thinking I was going to have to use hand loads in my Model 01, 02, and XM16E1 clones, or just live with Ball powder induced excessive bolt velocity and the battering that goes with it.

Well, looks as though the Serbs are to the rescue:


Reading the test results I see that the Serb ammo achieves proper velocity, lower port pressure, and we hope safe chamber pressure at the same time. So there you go, early 60's spec M193.

For those that don't know, the early 1960's AR-15 did not have a functional buffer, but instead used a lightweight recoil spring guide called an edgewater. If you don't have a light weight recoil spring guide then you may well have some issues using this ammo (as did the tester).
Link Posted: 3/15/2006 12:46:51 PM EST
Ya learn something new every day! I knew Stick (Stickman) became a ARFCOM dealer, but had no idea he had his own powder!
Link Posted: 3/15/2006 12:54:03 PM EST
Link Posted: 3/15/2006 12:56:16 PM EST
Link Posted: 3/17/2006 9:58:01 PM EST
[Last Edit: 3/18/2006 6:16:37 AM EST by Ekie]
IMR is a extruded powder or "stick powder". IMR4475 is what Remington loaded for ArmaLite for use in the AR-15. The original Colt/ArmaLite AR-15 used a edgewater recoil spring guide. This spring guide is significantly lighter then the buffer used from December 1966 on.


As we found very soon..the claims made for the ballistic performance of the .223/5.56 cartridge, by ArmaLite, Colt, Remington, Stoner, OSD (APRA) and other vocal proponents of it, had been considerably exaggerated...This should not have been surprising, because the powder capacity of the cartridge is simply insufficient to accommodate the necessary charge, of an IMR propellant of suitable relative quickness, to meet those ballistic requirements.

November 1963 Colt wins an award for 104,000 M16 and XM16E1 rifles.

Army seeks ammunition to go with rifle awards


All three commercial manufacturers promptly decline offers to bid on the M193 round as defined by the specifications.

Prior to acceptance individual rifles are tested to insure they meet cyclic rate specifications.

Tolerance limits for cyclic rate are set at 650-850 rpm.

March 24-25 1964 Colt reports that six out of ten exceed 850 rpm's with WC846, a Ball powder. One out of ten exceed 850 rpm with IMR4474.

In April 1964 the Air Force grants a waiver to extend rpm specs to 900 rpm for their M16 rifles. The Army grants Colt a monthly waiver extending the rpm limit to 900 rpm through out the Summer of 1964.

Ammunition loaded with CR8136 (extruded) is delivered to Colt for the sole purpose of acceptance testing and is delivered in August of 1964.

Army suspends the 900 rpm waiver because CR8136 meets cyclic rate specs.

December 1964 Remington drops CR8136. As with the prior extruded powder IMR4475 chamber pressure limits could not be met. Remington now loads with Ball powder, specifically WC846. WC846 Ball powder is now used by all three M193 manufacturers.

Colt runs out of CR8136 in the Spring of 1965.

September 1965 test results:

EX8208 (later named 8208M) extruded powder 854 rpm (used in production starting in June 1966)
WC846 Ball powder 880 rpm


During testing of production rifles, a marked change in the cyclic rate was observed to correspond with a change from ammunition employing tubular-grain propellant to ammunition employing spherical grain (ball) propellant....

November 1965 Testing shows ball powder increases cyclic rate 92-135 rpm over extruded powder.


The "bottom line" of Colt's Ammunition Variables report was that the cyclic rate of virtually all XM16E1s was acceptable with when tested with IMR-type powder, but that over half of these same rifles would exceed the limit and therefore be rejected if tested with ball propellant.


1. A difference in characteristics..can be observed. A significantly higher rate cyclic rate of fire is obtained with ball propellant. (75-130 rpm).


Springfield Armory ran a test of the new buffer from 13 April 1966 to 6 May 1966, concluding stubbornly that M16 performance using the new buffer and firing ball propellant, while now within the 850 rpm cyclic rate specification, was not as good as the past recorded performance using the old action spring guide and firing ammunition loaded with IMR CR8136. In any case the new buffer was subsequently adopted, first coming on the stream in December 1966.


..The project manager was responsible for furnishing Colt's with test ammunition. The cyclic rate phenomenon having been identified as a rifle-ammunition problem, which Colt's and the Committee expected to solve with a new buffer, the Project Manager directed to forego the use of WC846 for acceptance testing. He located all remaining lots of IMR [CR]8136-loaded ammunition and had them shipped to Colt's for use in future [XM16E1] testing. The effect was a de facto waiver of the Army's upper cyclic rate limit.


Meanwhile, acceptance test records at Colt's began to bear out the efficacy of the new buffer. Under the terms of contract "0018", one rifle was chosen at random out of every 10,000-rifle lot was routinely subjected to a 6,000-round endurance/acceptance test. From May to December 1966, 91,000 rounds loaded with CR8136 had been fired in rifle with the old buffers, with an overall malfunction rate of 0.49 per 1,000 rounds. From December 1966 to June 1967, 102,00 rounds loaded with WC846 were fired in rifle fitted with the new buffers for an average malfuntion rate of only 0.25/1,000 rounds.


In December 1966 as soon as the tale could be told without compromising the XM16E1 acceptance rate, Cot. Yount informed General Besson that acceptance testing at Colt's had for the last seven months been done exclusively with ammunition loaded with IMR CR8136 propellant. As expected, the immediate reply from AMC headquarters was an order to reintroduce ball-powder test ammunition as quickly as possible. By that time all of Colt's new rifles were fitted with the heavier buffer, which corrected the unacceptable high cyclic rates produced by ball powder's high port pressures.

THE BLACK RIFLE page 269 shows M16A1 test results with the newer heavy buffer.

WC846 815 rpm
IMR 8208M 650 rpm


Fifteen days of firing took place in January 1968, employing 522 Marine troops using M16A1 rifles with new buffers and both chromed and unchromed chambers, and firing ammunition loaded with both ball and IMR propellant.

AMERICAN RIFLEMAN April. 1968 page 42

........., the Deputy Secretary of Defense directed an extensive retest of recently manufactured M16 rifles and ammunition including current modifications to the rifle. This had been recommended by the investigating subcommittee. The test was carried out in January 1968. It showed a significant difference in the rifle malfunction rates with ammunition loaded with Ball and extruded propellants, the Ball being significantly better.

The Secretary of Defense on January 29, 1968 directed that until further notice no 5.56 mm. ammunition loaded with extruded propellant be manufactured, or distributed in Vietnam..........

AMERICAN RIFLEMAN Feb. 1978 page 38

However, in long trials an a final test ordered by the Defence Department, it was found that ammunition loaded with Ball powder gave significantly less malfunctions in this rifle then ammunition loaded with extruded powder (he is talking about the Ft Sherman test, Ekie). The Secretary of Defence thereupon directed that only Ball powder-loaded ammunition be supplied for all M16-M16A1 use in Vietnam, and that all future loading of 5.56 mm ammunition be with Ball powder....................

Link Posted: 3/18/2006 6:08:52 AM EST

Wow . . . .

Great compilation Ekie! Thanks!
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