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Posted: 10/8/2004 11:11:30 PM EST
As I was writing in another thread, I get really ticked, that evertime I mention an AR to someone who knows nothing about them, instantly, the story about Vietnam, and the unreliability issues comes up.

Naturally, I explain how Stoner designed the gas system to run on IMR propellants, and how the government switched to (cheaper) ball powder, causing the increase in fouling. Then I also go into the cleaning issue.

But is there more to the story? Is there anything else that caused all these problems? Especially as that now, the M16 (M4) is one of the most advanced and successful military rifles in the world.

Just curious,

Gundraw
Link Posted: 10/8/2004 11:26:17 PM EST
Most of the first M16's weren't chromed, fouling and pitting occured alot.
Link Posted: 10/9/2004 12:36:35 AM EST
case hardness, cycle time, and several other reasons also played a part.
Check out THIS link if you have te time, It'll answer all your burning questions. --ST
Link Posted: 10/9/2004 12:37:05 AM EST
Also, troops were actually told that the guns didn't need to be cleaned. This was reinforced by a virtually complete lack of cleaning kits early on.

To this day - despite all that I've read - I still cannot see that powder selection was a significant factor. I think powder was a convenient scapegoat. Virtually all ammo is loaded with ball powder nowadays. I understand how ROF related problems may be traceable to powder selection, but the vast majority of jams in the field were shown to have been associated with corrosion in the chamber.

Sam
Link Posted: 10/9/2004 1:09:20 AM EST
[Last Edit: 10/9/2004 1:09:43 AM EST by SchlaffTablett]
If you read the article at the link I posted, you'll see why the powder played such a role. It's not as simple as dirtier or faster burning powder like most people think.
Link Posted: 10/9/2004 1:34:45 AM EST

Originally Posted By Samuel_Hoggson:
Also, troops were actually told that the guns didn't need to be cleaned. This was reinforced by a virtually complete lack of cleaning kits early on.

To this day - despite all that I've read - I still cannot see that powder selection was a significant factor. I think powder was a convenient scapegoat. Virtually all ammo is loaded with ball powder nowadays. I understand how ROF related problems may be traceable to powder selection, but the vast majority of jams in the field were shown to have been associated with corrosion in the chamber.

Sam




ALong with using ball powder, non-chrome lining, and not being cleaned in the field, ever, moisture also played a big part in the problem.

Once the moisture penetrated the walls of the chamber, the bbl would be useless.
Link Posted: 10/9/2004 2:44:22 AM EST

Originally Posted By newbushmaster:

Originally Posted By Samuel_Hoggson:
Also, troops were actually told that the guns didn't need to be cleaned. This was reinforced by a virtually complete lack of cleaning kits early on.

To this day - despite all that I've read - I still cannot see that powder selection was a significant factor. I think powder was a convenient scapegoat. Virtually all ammo is loaded with ball powder nowadays. I understand how ROF related problems may be traceable to powder selection, but the vast majority of jams in the field were shown to have been associated with corrosion in the chamber.

Sam




Along with using ball powder, non-chrome lining, and not being cleaned in the field, ever, moisture also played a big part in the problem.

Once the moisture penetrated the walls of the chamber, the bbl would be useless.hr



All of the above, add in the M16 going through the development and design pains that every new
weapon platform goes through.

40 plus years and counting and the M16 / M4 is the king of combat rifles.

Uncle Sugar gave me a CAR, and i took care of it and it never failed me.
Link Posted: 10/9/2004 4:04:42 AM EST
Link Posted: 10/9/2004 5:28:29 AM EST

Originally Posted By 5subslr5:

Originally Posted By GunDraw:


Naturally, I explain how Stoner designed the gas system to run on IMR propellants............

and how the government switched to (cheaper) ball powder, causing the increase in fouling.

Gundraw



It wasn't that Ball powder was cheaper it was that the Army had 100 million rounds of Ball powder ammo stockpiled. (Never mind that the AR-15 was designed for IMR and Ball posed higher gas port pressures that caused all sorts of problems.)



5sub





Uhhhh....When it was first introduced as a new military cartridge, how did the Army have 100 million rounds already stockpiled?



Lonny
Link Posted: 10/9/2004 6:10:55 AM EST
[Last Edit: 10/9/2004 6:12:29 AM EST by 5subslr5]
Link Posted: 10/9/2004 6:35:33 AM EST
[Last Edit: 10/9/2004 6:43:34 AM EST by 45Colt]
Try this site for info about the history and development of the AR15/M16.
http://www.thegunzone.com/556dw.html


Sorry, I didn't see the hot link to the web site that was listed above.
45Colt
Link Posted: 10/9/2004 7:42:50 AM EST
[Last Edit: 10/9/2004 7:45:56 AM EST by A_Free_Man]
The powder was REMANUFACTURED powder made from older powder that had been stored in less than optimal conditions. It had begun to break down from the hot storage conditions. The nitric acid used in making the nitrocellulose was separating, acidifying the powder. Calcium carbonate (ground up limestone or shell) was added to absorb and neutralize the excess acid during the remanufacturing process. But they added too much calcium carbonate, which would build up in the gas tube.

Still, this was not the main problem. The main problem was rusted chambers.

Like the "tumbling bullet" story, people took a phrase they heard third hand about something they knew nothing about, and it became legend... "you don't have to clean it." Well, that is what bit them in the ass.

This probably came from two sources, either or combined:

(1) The rear of the bolt carrier is "self cleaning" in that excess carbon will build up and be blown out.

(2) Also, some think that you should not clean .22 calibres. This came from guys who target shot .22LR target rifles. After cleaning, it takes several rounds before the barrel settles back down and groups to point of aim. You have to fire a number of fouling shots before expecting proper performance. And bolt action target rifles will function on very little cleaning. This became, "never clean a .22".

However, the only thing the M16 had in common with .22LR bolt actions was the bore diameter. It was not a simple bolt action, it was a very complex select fire firearm. It was not being used in ROTC basement indoor gun ranges, but used in a most firearm hostile environment, high humidity and rain. These factors insure a rusting bore and chamber if not cleaned and oiled very regularly.

A third factor, a lot of city boys who had never handled a firearm before in their lives (and many have not since) were handed the most advanced rifle ever to hit the battlefield, with virtually no training in its upkeep. And a good number of these guys were not the highly motivated volunteers we have now.

Also, an investigation by Colt (Ito somebody) found that a large percentage of magazines were "unservicable". They were damaged, or full of twigs, leaves, dirt.
Link Posted: 10/9/2004 8:03:26 AM EST

Originally Posted By 5subslr5:

Originally Posted By GunDraw:


Naturally, I explain how Stoner designed the gas system to run on IMR propellants............

and how the government switched to (cheaper) ball powder, causing the increase in fouling.

Gundraw



Stoner did not design the AR-15. Jim Sullivan and Bob Fremont designed the AR-15. (Stoner did design the AR-10.) Stoner also did not design the Stoner 63. Sullivan and Fremont designed the Stoner 63. However, Stoner did design the Stoner 62. You'll quickly notice a trend with Stoner........he designed in 7.62 as he felt the 5.56 cartridge was not adequate for military use.

It wasn't that Ball powder was cheaper it was that the Army had 100 million rounds of Ball powder ammo stockpiled. (Never mind that the AR-15 was designed for IMR and Ball posed higher gas port pressures that caused all sorts of problems.)



5sub





I didn't say he designed the AR-15, but I thought he designed the gas system for it didn't he? I guess I remember hearing SOMETHING about there was a patent on "Stoner's" gas system, and they sold it to Colt. (which is where Stoner went after Armalite right?)

Yes, that makes sense, it was they had ball powder stockpiled, not that they could get it cheaper, that was my bad.

So the cleaning errors/non-chrome lining was really the biggest player in this whole fiasco... I see.

I had no idea about the "Remanufactured" powder. You'd think with all that at stake, there would have been test dummies running the stuff night and day in cold, heat, moisture you name it before sending it in with the troops. That's terrible.

Thanks for the info, the website if very thorough. I just was curious as to what all the problems were that they have obviously corrected by now.

Thanks everyone,
Gundraw
Link Posted: 10/9/2004 8:19:06 AM EST
Link Posted: 10/9/2004 9:12:28 AM EST
[Last Edit: 10/9/2004 9:20:10 AM EST by dewatters]
I appreciate the link to my Timeline. For those too lazy to wade through it, here is the condensed version related to the powder issue:

The villians in the "Great Powder Controversy" are not as clear cut as one is led to believe. DuPont's IMR powders predate Olin's Ball powders by two decades. IMR was 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 suspended 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 were 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 was not officially dealt with until the Fall of 1969. In January 1970, Olin took a further step and divided the tolerances of WC846. They finally discovered/admitted that lots of WC846 suitable for 5.56x45mm were at the opposite end of the tolerance range from lots suitable for 7.62mm NATO. Henceforth, the 5.56x45mm suitable tolerance range were relabeled as WC844. The 7.62mm NATO-suitable tolerance range remained known as WC846.
Link Posted: 10/9/2004 9:41:20 AM EST

Originally Posted By GunDraw:
You'd think with all that at stake, there would have been test dummies running the stuff night and day in cold, heat, moisture you name it before sending it in with the troops. That's terrible.



McNamara wanted to run the war like a corporation, so he did. That kind of testing was definitely not cost effective!
Link Posted: 10/9/2004 11:34:51 AM EST
This is a great thread. I'm not trying to be obtuse, but I'm still confused about the powder issue. OK, so the calcium issue wasn't dealt with till late '69. I thought that the unreliability issues (jamming) had been almost entirely solved well before late '69? How did the early changes in propellant type, allowable pressures, burning rates, etc. improve reliability?

Sam
Link Posted: 10/9/2004 1:40:19 PM EST

Originally Posted By El_Roto:

Originally Posted By GunDraw:
You'd think with all that at stake, there would have been test dummies running the stuff night and day in cold, heat, moisture you name it before sending it in with the troops. That's terrible.



McNamara wanted to run the war like a corporation, so he did. That kind of testing was definitely not cost effective!



+1. Robert McNamara was the smartest dumbass that ever lived.

Fuck him forever.
Link Posted: 10/9/2004 1:47:41 PM EST
Link Posted: 10/9/2004 1:55:47 PM EST
We kept our M16's well fed and well cleaned. They didn't have any problems but I got constipated eating C-Rations. End of story.
Link Posted: 10/9/2004 4:37:39 PM EST

Originally Posted By RAMBOSKY:
We kept our M16's well fed and well cleaned. They didn't have any problems but I got constipated eating C-Rations. End of story.




Ditto for our M-16s. Funny thing about those C-Rats. They had just the opposite effect on me; but that's a whole different tail,er, I mean tale!
Link Posted: 10/9/2004 6:14:07 PM EST
After reading the excellent powder explanation you wrote up dewatters, I have a couple questions.

First, I'm not familiar with the XM16E1, at first, I thought this was the military designation for the M-16 perhaps, but then I see later in the article, it is different. What is this?

Second, what causes the difference in cyclic rates? I figured it would be the gas port pressure, but I noticed some powders did not increase the cylic rate but had increased gas port pressure, CR8136 for instance) . Is high gas port pressure bad? I guess I dont' fully know how the gas port pressure, and the cylic rate effect the weapon. Is the higher cylic rate just a heat problem?


And now my main question/observation:
The IMR 4475 was not acceptable because they couldn't keep the pressure up (read: couldn't keep long range velocity up)

Then WC 846 was used just temporarily until CR8136. (and the WC 846 was dropped because of the increase in cylic rate), but then switched BACK to WC 846 when the CR8136 wouldn't mainting the maximum pressure... AGAIN (so basically, they were having the SAME problems as the 4475 right?)

But then ended BACK up with WC 846 (along with the higher cyclic rate) when 8208M didn't work out.

So overall, it seems it was pick the poison, either too high a cyclic rate with the WC 846, or unacceptable pressure variations with both IMR4475 or CR8136.

Gundraw

5sub, that makes sense, but did Stoner design the gas system? The way it sounds, Stoner didn't have NEAR as much to do with the m16 as I and most think/thought.
Link Posted: 10/9/2004 8:31:08 PM EST
[Last Edit: 10/9/2004 8:32:15 PM EST by A_Free_Man]
It all has to do with burning rate, and how and when the peak pressure occurs.

A fast powder may peak quickly, causing high chamber pressure, but still not deliver high muzzle velocity.

A slow powder might give good muzzle velocity, burning smoothly and evenly but not give enough port pressure. I have seen this with IMR4350 (a very slow powder) in .30-06, good muzzle velocity, but inconsistent cycling. Changing to IMR4064 (a faster powder) improved functioning, but reduced velocity slightly.

With a semiauto, or in the case of the M16, full auto, functioning is as important as muzzle velocity. Both criteria must be satisfied.
Link Posted: 10/9/2004 9:45:26 PM EST
Free_man - I get what you mean about pressure consistancies, peaks, and burn rate and the relationship (or lack there of) between peak pressure and velocities... I reload all my ammo and have looked over these things to a fair extent. My intent in my message, is that from what I understood from dewatters post, is that the powder, at it's peak pressure, was not producing enough velocity. Or was it the actual functioning that was the problem (too quick of pressure peak, therefore low port pressure)?

So are you saying that the maximum port pressure is best? I didn't know if maybe there could be TOO much (perhaps if that was part of a cause of an increased cyclic rate) port pressure.

These were just minor questions I was trying to clear up.

Gundraw

P.S. I'm addicted to IMR 4350 in my bolt guns, however, I would agree, in autoloaders, it's an uphill battle.
Link Posted: 10/10/2004 3:35:23 AM EST
[Last Edit: 10/10/2004 3:40:05 AM EST by dewatters]

Originally Posted By GunDraw:
After reading the excellent powder explanation you wrote up dewatters, I have a couple questions.

First, I'm not familiar with the XM16E1, at first, I thought this was the military designation for the M-16 perhaps, but then I see later in the article, it is different. What is this?



The XM16E1 was redesignated the M16A1 with its classification as 'Standard A' in February 1967.


Originally Posted By GunDraw:
5sub, that makes sense, but did Stoner design the gas system? The way it sounds, Stoner didn't have NEAR as much to do with the m16 as I and most think/thought.



The following is from my next Timeline update:

August 1956: Gene Stoner files a patent application for the gas system and bolt carrier design later used in the AR-10 and AR-15.

September 1960: Gene Stoner receives US Patent #2,951,424 titled "Gas Operated Bolt and Carrier System."

(Note: Click on "Images" to view the patent documents. You'll need a program that can view .TIFF files, such as Apple's Quicktime or AlternaTIFF. I prefer the latter since you can save and print the images.)
Link Posted: 10/10/2004 4:51:57 AM EST
Having lived through that time span while in the US Army, I will weigh in with what I recall…

1965-66 Problems surfaced when units in Viet Nam were issued M16s in quantity. The first I heard of a statement indicated 6 changes were forthcoming to resolve reliability issues.

I only recall the chrome plating of the chamber and a "change" in the buffer assembly to reduce the cyclic rate of fire. The others I cannot recall.

A new Field Manual was issued which was about 5 times larger than the original. The extra pages were expanded Immediate Action and Maintenance chapters.

As was pointed out, cleaning kits and supplies were hard to find. Chamber brushes were rare and my Infantry squad could boast of having 2 cleaning rods for 10 men!

There was no such thing as LSA, CLP or any of the lubricants available today. All we had was Weapons Oil and Grease.

To think that an infantryman in combat doesn't clean his weapon is ludicrous! If you examine pictures of WWII, Korea, Viet Nam you will see soldiers in various states of filth but you will never see a dirty weapon!

When our ammo looked questionable, we discarded it and loaded fresh. I would bet we threw away more than we ever fired!

I am sure that the lubricants we used and perhaps the ball powder were the cause of the problems we had.

But let's put "fail" into perspective. I only recall actually seeing 3 failures in one year. That was at two different times and not the same rifle… In one case, once the stuck case was removed the weapon functioned OK. The second time, another case stuck after a few more rounds but then worked. Both cases were semi-auto firing with clean weapons.

While these took place in a firefight making it pretty exciting, it hardly damns the M16 of that era.

Still not a confidence builder but no one snickered at my instance of fixed bayonets during a firefight or on ambush…

As a side note, in that same battle, the unit that was overrun had more failures than we did. They did much more firing than we did, many running out of ammo or failure due to battle damage. Some of them reverted to bayonets, machetes or entrenching tools.

As the artillery BN (9, 105mm howitzers) ran out of ammo, they formed rifle squads and helped retake overrun portions of the perimeter. They didn't have much ammo for their M14s but did one fine job!

All things considered, it was a very busy morning.
Link Posted: 10/10/2004 7:42:21 AM EST
[Last Edit: 10/10/2004 7:43:41 AM EST by RAMBOSKY]

Originally Posted By RAMBOSKY: "We kept our M16's well fed and well cleaned. They didn't have any problems but I got constipated eating C-Rations. End of story.

Originally posted by TangoRomeo: "Ditto for our M-16s. Funny thing about those C-Rats. They had just the opposite effect on me; but that's a whole different tail,er, I mean tale!



You chewed the pack of "Chickletts" that came with the C-Rations. They were exlax! I didn't want to be caught with my pants down at the wrong time so I never chewed them.
Link Posted: 10/10/2004 8:16:19 AM EST
Link Posted: 10/10/2004 9:24:34 AM EST
Thanks, 5sub. That kinda ties up the loose ends for me. It sounds like powder burn rate was a contributory factor only in the context of a rough, possibly corroded/dirty chamber. Increased ROF related to burn rate could result in an FTextract when extraction commences prior to relaxation of the case. This would have less to do with ball vs extruded powder (or even Calcium), and more to do with the specific burn rates of what was available at the time. (?)

Makes me wonder: if cleaning kits had been universally available and chambers chromed from the first would there have been a problem at all?

Sam
Link Posted: 10/10/2004 3:31:58 PM EST
Gundraw/A Free Man:

I don't have a Garand, but I'm told (see page 10 of this article) that using anything slower than 4064 in a Garand or M14 is dangerous due to the gas port thing. That said, 4064 and 4895 should be OK. I use 4895 in my AR, and I'm told 4064 works good too even though I haven't tried it yet.


Parrot 32:

Thanks for the story!


Everyone:

Great thread! Thanks for putting your knowledge on it!
Link Posted: 10/10/2004 5:31:41 PM EST

Originally Posted By RAMBOSKY:

Originally Posted By RAMBOSKY: "We kept our M16's well fed and well cleaned. They didn't have any problems but I got constipated eating C-Rations. End of story.

Originally posted by TangoRomeo: "Ditto for our M-16s. Funny thing about those C-Rats. They had just the opposite effect on me; but that's a whole different tail,er, I mean tale!



You chewed the pack of "Chickletts" that came with the C-Rations. They were exlax! I didn't want to be caught with my pants down at the wrong time so I never chewed them.



Holy Montezuma's Revenge! I knew those things tasted odd, but I thought they were just old!
Link Posted: 10/11/2004 8:06:03 AM EST

Originally Posted By A_Free_Man:
It all has to do with burning rate, and how and when the peak pressure occurs.

A fast powder may peak quickly, causing high chamber pressure, but still not deliver high muzzle velocity.

A slow powder might give good muzzle velocity, burning smoothly and evenly but not give enough port pressure. I have seen this with IMR4350 (a very slow powder) in .30-06, good muzzle velocity, but inconsistent cycling. Changing to IMR4064 (a faster powder) improved functioning, but reduced velocity slightly.

With a semiauto, or in the case of the M16, full auto, functioning is as important as muzzle velocity. Both criteria must be satisfied.



Running 4350 or powders of that speed range in a Garand will beat up op rods. The 30-06 case is large enough to take advantage of slower powders in this burning range, but when doing so you get too high port pressure. That's why 4064/4895 are the powders typically used -- they don't provide max velocity but they work well with the gas and op rod system.

I suppose it would be theoretically possible to continue going to a slower powder yet, maybe something designed for 50 BMG. You would get to the point that max pressure wouldn't be achievable so port pressures would back in the OK area, but velocity would suck and fouling would be terrible.
Link Posted: 10/11/2004 9:59:10 AM EST
Yeah, we tried 4350 because it worked so well in bolt guns. But we had functioning problems. 4064 gave much greater reliability of function, as did 4895, an old favorite in the 7.62. I was using those as real world examples.
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