[SodaPop]

I've heard people say that when we switched to the A2 we started using hotter ammo. How much hotter did it get?

[Art Eatman]

I'd be sorta dubious. Hotter than "early days" could go to popping primers, which is rather uncool.

You also gota consider gas-port location and size of the port. Don't want bolts slamming back too hard. The difference between the early M16s and the A2? Dunno.

Art

[SodaPop]

Its another History Channel reference.

They said, "switching to a different powder increased range and effectiveness."

[Detritus]

Its another History Channel reference. They said, "switching to a different powder increased range and effectiveness."

this REALLY sounds like a case of "mixed up time line/ who and what said change was done for"

there have been TWO major powder switch-ups in the history of the AR-15/M-16. and possibly some minor changes since..

The first mandated by the DoD was from extruded "stick" powder for which the gun was designed to the older style "Ball" powder with a longer pressure curve and dirtier burn. this was done because the longer pressure curve upped the FPS of the 55gr FMJ to the point where it could meet the "penetrate steel helmet at X number of yards" requirement the army dreamed up, this also allowed the use of the HUGE stores of ball-type rifle powder to be utilized instead of instantly rendering them obsolete. (this change was fought tooth and nail by everyone truly familiar with the guns operating system and how sensitive it was to fouling)

the Second major change came when it was realized that the older ball powder was a significant contributor to the excessive fouling and attendant jamming in combat that was experienced during the first portion of the M-16's employment in Vietnam (the reasons for this can be found in earlier discussions of the M-16 and it's woes). at this time they changed BACK to the orginal extruded (stick) powders due to the massive reduction in fouling, and leap in reliability this allowed.

later, about the time the A2 was developed, better AP and tracer rounds were developed that were heavier than the original spec, THESE (esp the AP, since with the switch back to extruded powder, the extra "oomph" from the ball powder that let the regulkar FMJ meet the "steel helmet test" was lost) may have received different types of extruded powder that were more suited to their weights etc, but the major change made in the "system" was to use a different twist in the barrel, so as to better stabilize them.

the above quote from DSC seems to me to reek of a quote placed out of sequence or a misunderstanding of the evolution of the military round(s).

[Pumpkinheaver]

modern military M855 5.56 ammo I beleive is loaded with a 62gr bullet vs. the 55gr bullet of the older M193 ammo

[Futo Inu]

"this change was fought tooth and nail by everyone truly familiar with the guns operating system and how sensitive it was to fouling"

In fact, on the history or discovery channel the other day (forget which), on the AK v AR show, they showed a 1990 or 91 interview where they had both Eugene Stoner and M. Kalishnikov together. Mr. Stoner explained his adamant opposition to the powder switch you describe.

[Nando Aqui]

Read All About It Here:

http://www.ammo-oracle.com/

Enjoy!

Alex

[Nightcrawler]

I suppose, energy wise, SS109 had a little bit going for it over 55 grain ball, but only due to the heavier bullet, I would suspect. I don't think one is significantly more powerful than the other.

[SodaPop]

I picked up WC844 and shoot the M855 clone loads all the time. I did some research a few years ago and found 1 duplicate load for the M855 (26.1gr of WC844) and the M193 gave two loads. I did a search on TFL and couldn't find the exact loading info again. I just know (from several sources) that there are several M193 loads. Maybe one of them is for the SAW?

Also. I have a relative that said the ammo they used in the 80's wasn't as hot as the ammo they are using now. I'm sure I'm gonna get flamed for taking his word, but he's not the type to talk about something he doesn't know about.

[Shawn Dodson]

The M855 cartridge, using the 62 grain SS109 penetrator projectile, was originally designed by Fabrique Nationale for the FN Minimi M249 Squad Automatic Weapon.

The M855 was backfitted into the M16 rifle to facilitate commonality of ammunition between the M16 and the M249.

[Badger Arms]

Here's what I found interesting:

Distance to 2700 FPS.....20" Barrel.....16" Barrel.....14.5" Barrel.....11.5" Barrel
M193.....................190-200m.......140-150m.......95-100m..........40-45m
M855.....................140-150m.......90-95m.........45-50m...........12-15m

BTW, to answer your question, there is no essential velocity difference. The mil-spec is still the same. The velocity goes down as barrel length goes down. The M193 ammo loses much more velocity with shorter barrels and has a lower BC which means it also slows down faster. Slower 'midget bullets' gives us much decreased killing power. Below 2700fps, both bullets start acting like hole pokers and losing their magic hydrostatic fragmentation properties. No, flamers, don't reply and tell me I just said that an M-4 is only good out to 50 meters. This is just a round number and a reasonable place to start.

[Nightcrawler]

Funny you should call it "magic" fragmentation, becuase that's what it seems to be. I've been unable to determine whether it happens all the time, or just (conveniently) in enemy soldiers. *shrug*

In any case, being a heavier bullet with more solid construction, SS109 green tip might be less likely to fragment, too.

[uglygun]

I'm a fan of the M193 loads personally, being a velocity freak and all.


The other thing, the M193 load is said(and I would believe it) to be marginally superior to the M855 load when it comes to defeating harder materials, materials lighter than hard armor atleast. The additional velocity of the M193 load helps it overcome the fact that it is composed of an all lead core, seems that the steel penetrator in the M855 load really only comes into play at longer distances where the heavier 62grn bullet is holding out a velocity/retained energy advantage to the 55grn bullet.

A bit of shooting against various steels seems to show a slight edge to the M193 at closer distances.



As for current powders, Win 748 and H335 both seem to do pretty good jobs of coming up with M193 load duplication. Can definitely get velocities up there with both of those powders, pretty sure the mil. M193 loads are done with a ball powder as well.

Interesting thing is how ball powders and cylinderical powders vary when it comes to temperature sensitivity. Ball powders seem to be more teperature sensitive, really big difference between loads developed in summer to those same loads shot during winter.

IMR cylindericals seem to be more stable.

[Daniel Watters]

Two issues:

1) The M855 was effectively thrust upon the US with NATO's 1980 standardization of the FN SS109. Prior to this, the US Army's 5.56mm SAW candidates were tested with other ammo types. As early as 1969, these experiments were conducted with the 68gr XM287 Ball and XM288 Tracer produced by Industries Valcartier Inc. (IVI) of Canada. In 1976, the XM287 Ball and XM288 Tracer were redesignated XM779 and XM780 respectively. However, by this point, the IVI cartridges were effectively replaced by 'in-house' designs, the XM777 Ball and XM778 Tracer. The latter pair could be used in standard 1-12" twist barrels. XM777 Ball and XM778 Tracer were submitted by the US to the late '70s NATO trials.

2) The villians in the "Great Powder Controversy" aren't as clear cut as one is led to believe. DuPont's IMR powders predate Olin's Ball powders by two decades. IMR is merely an improvement over DuPont's earlier Military Rifle (MR) series of powders such as Pyro DG. From the mid-'20 until the mid-'50s, IMR powders were the US military's primary choice for loading .30-'06 among other cartridges. During the same time frame, the only major US military use of Ball powder was in the .30 Carbine. The tide began to shift toward Ball powders in the '50s; indeed, as early as 1954, the Chief of Ordnance wanted every small arms cartridge to be loaded with it. This said, other powders continued to be used. For instance, Remington would often load 7.62x51mm ammo with IMR, supplied by its parent company DuPont.

During early (1957) load development for ArmaLite, Robert Hutton used IMR 4198, IMR 3031, and an unnamed Olin ball powder. At this point, the main goal was to show that the 55gr bullet @ ~3,300fps could indeed penetrate a helmet at 500yds. However, all of this testing was performed with a 22" barrel.

When Remington delivered the first lots of .222 Special (later renamed the .223 Remington), the cartridges are loaded with IMR 4475. (Ironicly, this is one of the same IMR powder types used by Remington for production of military 7.62x51mm cartridges.) Use of IMR 4475 with the smaller cartridge continued on through to the early '60s with early military production lots.

When the military adoption of the M16/XM16E1 was forced in 1963, Frankford Arsenal quickly found that IMR 4475 could not reliably achieve the quoted 3,300 fps from a M16 without going exceeding with quoted maximum chamber pressures. It was one thing when Remington was turning out small quantities of .223 Remington and could cherry-pick suitable production lots of IMR 4475, and quite another when it faced mass production of the cartridge. The choices were either to lower the velocity, increase the acceptable pressure specs, or change powders. The representatives from the Office ot the Secretary of Defense (OSD) to the Technical Coordinating Committee (TCC) vetoed lowering the velocity specs. It was warned that increasing the chamber pressure specs would be technically unwise given trials in which the cartridges were already prone to popping primers. When the earliest bid solicitations for M193 Ball were released later in the year, the OSD-sponsored specs demanded 3,250fps with a Remington-style 55gr FMJ (instead of the original Stoner/Sierra design), IMR 4475, and no change in pressure specs. In return, Remington, Olin/Winchester, and Federal all refused to bid.

By early 1964, M193 specs were given a temporary waiver. The average chamber pressure limit was increased to 53,000psi, with individual rounds allowed to test as high as 60,000psi. In response, Remington and Olin agreed to supply 500,000 cartridges apiece under this waiver. Frankford Arsenal also received permission to test production lots of 25,000rds loaded with alternate powders. Candidates included DuPont's CR 8136, Hercules' HPC-10, and Olin's WC846. (The latter was then in use by Olin for military production of 7.62x51mm ammunition, just as Remington had once done with IMR 4475.) Soon afterwards, Remington and DuPont complicated matters by withdrawing IMR 4475 for use in future production lots of M193.

HPC-10 was rejected due to low temperature pressure issues along with its propensity for bore erosion. WC846 had been an early favorite in part due to USAF acceptance of ammo lots loaded with the Ball powder. However, the resulting higher cyclic rate was ignored by the USAF, who simply increased the M16's maximum acceptable cyclic rate to match. The Army was more concerned, but issued month-by-month cyclic rate waivers for their XM16E1 instead. Soon after, DuPont's CR 8136 was also approved for use in loading M193. Although it also displayed higher pressure levels at the gas port, CR 8136 did not have as dramatic effect upon the cyclic rate as did WC846. As soon as Remington had production lots of M193 with CR 8136 available, the Army withdrew the month-to-month cyclic rate waivers for the XM16E1. Unfortunately, like IMR 4475 before it, the performance of CR 8136 was not stable from lot to lot, and Remington had a difficult time maintaining the maximum chamber pressure specs. By Decemeber 1964, Remington and DuPont withdrew CR 8136 for the production of M193. In order to finish the remainder of their production contract, Remington sought permission to use WC846, and this change was duly approved. However, XM16E1 acceptance testing at Colt continued with the remaining stocks of CR 8136-loaded M193 cartridges.

Colt's supply of CR 8136-loaded ammo did not run out until the early summer of 1965. When the Army refused to grant additional cyclic rate waivers with the use of WC846-loaded ammo, Colt in turn suspends production of the XM16E1 in favor of the USAF's M16. This led to yet another search by Frankford Arsenal for an alternate powder. While Olin declined to participate, two other powders were submitted: DuPont's EX 8208-4 and Hercules' HPC-11. DuPont's EX 8208-4 displayed moderate fouling, but it also recorded higher gas port pressures than even WC846. Hercules' HPC-11 showed the least visible fouling, but closer examination unveiled that heavy fouling was constricting the gas tube. Frankford Arsenal's final report recommended that EX 8208-4 be approved for use in M193 Ball and M196 tracer cartridges, and that Hercules and Olin reduce the fouling characteristics of their respective powders. Unlike WC846, HPC-11 was not approved for use. However, M193 and M196 cartridges loaded with DuPont EX 8208-4 would not enter the supply chain until June of 1966.

In December 1967, WC846 was withdrawn for use in loading M196 tracer cartridges. WC846 was replaced by DuPont's IMR 8208M (formerly EX 8208-4). Ironicly, production lots of M193 Ball loaded with IMR 8208M are soon withdrawn for practice use only. Reliability problems had been discovered in a new set of performance trials conducted by the USMC at Fort Sherman in Panama. Part of the goals were to sort out the relative merits of Ball versus IMR powders in the reliability of the M16A1.

The issue of allowable calcium carbonate content is not officially dealt with until the Fall of 1969. In January 1970, Olin takes a further step and divides the tolerances of WC846. They have finally discovered/admitted that lots of WC846 suitable for 5.56x45mm are at the opposite end of the tolerance range from lots suitable for 7.62mm NATO. Henceforth, the 5.56x45mm suitable tolerance range would be relabeled as WC844. The 7.62mm NATO-suitable tolerance range would remain known as WC846.

[SodaPop]

I think I got the answer I was looking for:


"Data for the M193 throws a lead core 55 gr. FMJ-BT bullet with a canalure and exposed lead base at 3,250 fps at a chamber pressure of 52,000 psi.

The M855 delivers a 62 gr. FMJ-BT with a steel penetrator in front of the lead core. It also is an exposed lead base design and has a muzzle velocity of about 3,100 fps with a chamber pressure of 55,000 psi. So it does have a bit hotter chamber pressure.

The M855 produces 1326 ft. pounds of energy at the muzzle. The M193 produces 1288 ft. pounds of energy at the muzzle. So the M855 produces a bit more energy than the M193."

[WonderNine]

Now imagine the stupidity of the army switching from 55gr. projectiles out of a 20" barrel that fragment and blow an exit hole through you the size of a grapefruit to....

a 62gr. glorified .22 magnum out of a 10" barrel. :rolleyes:

[SodaPop]

I somewhat agree, but the M855 would have been needed if we had to go up against the Soviets.