What was the original powder used in AR-15/M-16?

[ShtrRdy]

I think I read or heard that one of the IMR powders was the preferred choice for AR-15/M-16 cartridges but I don't recall which one. Do you know what the original load was?

 

[M1A1ABRAMS]

I did find this,you may find interesting ?
After a visit to Fort Benning, Stoner begins to tweak the .222 Remington round to fit the Infantry Board's penetration requirements. First, Stoner and Sierra's Frank Snow modify the .224″ 68 grain "M1 ball homologue" to 55 grains by shortening the bearing length and the boattail, while maintaining the original 7-caliber ogive and 9-degree boattail. The new projectile is also produced by Sierra. Robert Hutton uses Speer's Ballistic Calculator to estimate the muzzle velocity need to provide the desired performance at 500 yards. The results indicate a muzzle velocity of 3,300 fps with the 55 grain bullet will be required. Hutton begins load development with IMR 4198, IMR 3031, and an unnamed Olin ball powder. Using a Remington Model 722 with a 22″ Apex bull barrel and a Lyman 25x scope, Hutton successfully perforates US helmets at 500 yards during a public demonstration. However, testing also indicates that the .222 Remington cannot achieve the required velocity without excessive chamber pressure. Stoner contacts Winchester and Remington about increasing the case capacity; Remington accepts the request. (This refusal is hardly surprising since Winchester had their own SCHV rifle and cartridge in the works.) The resulting cartridge is designated the .222 Special.

https://looserounds.com/556timeline/

 

[Pdyson]

The powder selected in the design of the m16 was DuPont IMR 4475. The first M-16s went to the Green Berets and they worked flawlessly. Unfortunately, the Military had a gun powder contract with Olin and the switched to powder to WC846 which got a lot of GIs killed.

There is a good article on pew pew tactical that goes into all the failures of the m16 .

How And Why The M16 Failed In Vietnam (And Is It Reliable Today?)

How bad was the M16 during the Vietnam War? And can you trust it (and the civilian AR-15 variants) today? We cover it all.

www.pewpewtactical.com

 

[ShtrRdy]

Thanks for the info and the links guys!

 

[M1A1ABRAMS]

The powder selected in the design of the m16 was DuPont IMR 4475. The first M-16s went to the Green Berets and they worked flawlessly. Unfortunately, the Military had a gun powder contract with Olin and the switched to powder to WC846 which got a lot of GIs killed.

There is a good article on pew pew tactical that goes into all the failures of the m16 .

How And Why The M16 Failed In Vietnam (And Is It Reliable Today?)

How bad was the M16 during the Vietnam War? And can you trust it (and the civilian AR-15 variants) today? We cover it all.

www.pewpewtactical.com

It is discovered that IMR 4475 cannot reliably achieve the quoted muzzle velocity of 3,300 fps within the accepted maximum chamber pressure specs. At the same time, Olin-Winchester is proposing a new cartridge, the .224E5. The .224E5 and its predecessor, the .224E4, are both based on the .25 Remington case, shortened to fit within the same action length as the .223 Remington. However, the .224E5 possesses a rebated rim so that existing .223 Remington bolt faces need not be altered. (Oddly enough, these cartridges bear more than a passing similarity to the .219 Donaldson Wasp, albeit without a rim.)
"Cartridge, 5.56mm Ball, M193" is officially type-classified. Pushed by OSD over the objections of the TCC, it specifies the Remington-designed projectile, a muzzle velocity of 3,250 fps, IMR 4475 powder, and the existing average 52,000psi pressure limit. Remington, Olin, and Federal Cartridge all refuse to offer bids. Olin objects to certain specifications on cartridge case wall thickness and to the specifications of IMR 4475 propellant. Remington objects to the same case specifications and recommends that the prescribed maximum mean chamber pressure be increased from 52,000psi to 53,000psi. Federal Cartridge expresses the view that the maximum mean chamber pressure should be
raised to 54,000psi.

Remington and Olin-Winchester representatives meet at Frankford Arsenal to discuss possible relaxation of primer sensitivity limits. They are reluctant to accept any limits other than 12-60 in-oz. Frankford indicates that this is unacceptable. Remington counters that a 12-48 in-oz limit will result in rejection of 50 percent of the primers. Olin-Winchester's predictions are far worse, estimating that 2 out of 3 primer production lots will be rejected. This is later amended to estimate rejection of 90 percent of the primers.
Frankford Arsenal notifies Olin, Remington, and Federal that both CR 8136 and WC846 will be approved as permissible alternates to IMR 4475 in the loading of 5.56mm M193 ball ammunition.

 

[SAR Chief]

It is discovered that IMR 4475 cannot reliably achieve the quoted muzzle velocity of 3,300 fps within the accepted maximum chamber pressure specs. At the same time, Olin-Winchester is proposing a new cartridge, the .224E5. The .224E5 and its predecessor, the .224E4, are both based on the .25 Remington case, shortened to fit within the same action length as the .223 Remington. However, the .224E5 possesses a rebated rim so that existing .223 Remington bolt faces need not be altered. (Oddly enough, these cartridges bear more than a passing similarity to the .219 Donaldson Wasp, albeit without a rim.)
"Cartridge, 5.56mm Ball, M193" is officially type-classified. Pushed by OSD over the objections of the TCC, it specifies the Remington-designed projectile, a muzzle velocity of 3,250 fps, IMR 4475 powder, and the existing average 52,000psi pressure limit. Remington, Olin, and Federal Cartridge all refuse to offer bids. Olin objects to certain specifications on cartridge case wall thickness and to the specifications of IMR 4475 propellant. Remington objects to the same case specifications and recommends that the prescribed maximum mean chamber pressure be increased from 52,000psi to 53,000psi. Federal Cartridge expresses the view that the maximum mean chamber pressure should be
raised to 54,000psi.

Remington and Olin-Winchester representatives meet at Frankford Arsenal to discuss possible relaxation of primer sensitivity limits. They are reluctant to accept any limits other than 12-60 in-oz. Frankford indicates that this is unacceptable. Remington counters that a 12-48 in-oz limit will result in rejection of 50 percent of the primers. Olin-Winchester's predictions are far worse, estimating that 2 out of 3 primer production lots will be rejected. This is later amended to estimate rejection of 90 percent of the primers.
Frankford Arsenal notifies Olin, Remington, and Federal that both CR 8136 and WC846 will be approved as permissible alternates to IMR 4475 in the loading of 5.56mm M193 ball ammunition.

After my return from RVN, I read an Army report saying the powder was too slow burning and the cellulose in the powder was clogging the gas ports. This was my experience. Wish like hell I could locate the report and put all this other BS to rest. The original powder/bullet/primer/brass was made by (I can not remember the mfg. of the ammo for testing) and no failures in testing in Maryland. Then ammo was put up for bid. All the ammo had to do was make the Mil Spec FPS/bullet weight. There must be a dozen different burn rates that will meet the Mil Spec for a 55 gr. bullet. There is so much BS surrounding the so called "failure" of the 16' in RVN. I was there all year, 1969. Attached to 173rd. I cleaned daily, no failures in M-60, 16 ga. rem pump, and the m-14 I started with, and the M-16 I finished with. I like claymores and the M-79. [IMR stands for "Improved Military Round"]