Do any rifles besides the Armalite rifles use a DI gas system?

[migkillertwo]

subject.

 

[JHK94]

Ljungman rifle.

 

[Justin]

The vast majority of M-16 and AR-pattern rifles use Direct Impingement for their operating system.

 

[Nom de Forum]

The French used DI rifles for several decades

MAS 49 and MAS 49/56

 

[W L Johnson]

The vast majority of M-16 and AR-pattern rifles use Direct Impingement for their operating system

Which are designed by Armalite or based on Armalite designs. I think his question is anything other than these.

 

[txhoghunter]

Which are designed by Armalite or based on Armalite designs. I think his question is anything other than these.

OTOH, there are AR style firearms that do not use a DI gas system.

 

[W L Johnson]

yes, but I think his question is "what other rifles that are not AR's us DI. Or at least that's how I read it, not trying to be rude, just helpful, sorry if it may comes across as rude.

 

[Jeremy2171]

Hakim and Rasheed.....

 

[Polar Express]

Hakim and Rasheed

That would be one definition of 'direct impingement'.....

PE

 

[Magog]

I like the DI gas system.

Replacing all that heavily metal keeps the rifle light.

Yes, even piston systems need to be cleaned.

No mater how heavy they are.

 

[Slamfire]

I think all the rifle systems that use DI have been listed.

If you notice, they are all old and out of inventory, with the exception of the M16/M4 series of rifles.

Evolution has run its course, and DI is an evolutionary dead end.

DI is simple and cheap. That is its advantages. I will also add that the system provides a basis for a very accurate action as there are less moving parts to cause vibrations in the system. However target grade accuracy is only an issue for target shooters. Military and police are not trained to a high enough level to take advantage of a target rifle , and apparently, war is different from shooting at paper bullseyes or foam pop up targets.

The greatest disadvantage of the system is that it is dirty. DI is a dirty system and blows residue directly into the mechanism. This is not a problem for barracks troops with plenty of time on their hands, but for troops in the field, the high maintenance required to keep a DI system functioning is undesirable in a combat weapon.

The Swedish action, the Ljungman rifle, actually required lubricated ammunition to function. Since I don’t have one, I don’t know if that is because of the DI system or something else.

 

[marktx]

The Daewoo K1 rifle also uses a direct impingement system, not sure without looking it up but I think the bolt carrier is a copy of the M-16. The Koreans changed to a piston system with the K2.

The Swedish action, the Ljungman rifle, actually required lubricated ammunition to function. Since I don’t have one, I don’t know if that is because of the DI system or something else.

Where did you get this information? Not saying it's wrong but I have never had any problem with a Ljungman or Hakim.

 

[Ithaca37]

I think all the rifle systems that use DI have been listed.

If you notice, they are all old and out of inventory, with the exception of the M16/M4 series of rifles.

Evolution has run its course, and DI is an evolutionary dead end.

DI is simple and cheap. That is its advantages. I will also add that the system provides a basis for a very accurate action as there are less moving parts to cause vibrations in the system. However target grade accuracy is only an issue for target shooters. Military and police are not trained to a high enough level to take advantage of a target rifle , and apparently, war is different from shooting at paper bullseyes or foam pop up targets.

The greatest disadvantage of the system is that it is dirty. DI is a dirty system and blows residue directly into the mechanism. This is not a problem for barracks troops with plenty of time on their hands, but for troops in the field, the high maintenance required to keep a DI system functioning is undesirable in a combat weapon.

And yet the Stoner platform is widely used across the world. Also, the notion that the weapon requires high maintenance is 100% false. Properly lubed it will run fine for longer than any engagements will last. Proper lubrication is a requirement for reliable functioning of any machine whether an M4, Kalashnikov, or your car.

 

[Slamfire]

Where did you get this information? Not saying it's wrong but I have never had any problem with a Ljungman or Hakim.

From these posts and section 11 of the the translated Service Manual. A link to the Service Manual is at the bottom.

http://forums.gunboards.com/showthread.php?70299-The-AG-42-For-Slowfire-Prone-And-Offhand


ACarpenter,

I've gone back and forth on the lubricated cartridges. I started doing it based on recommendations from others, then stopped because of new information I got that it's bad to lube cases because it puts undue stress on the bolt face. Lately, I've done some testing that has convinced me to lubricate the cartridges from now on.

I've been taking measurements of unfired cartridges and cases that were fired in my Ljungman. I'm using a Hornady Lock-N-Load cartridge headspace gauge attached to my digital calipers.

I've determined that the headspace on my Ljungman is on the long side. It will not close on a Field headspace gauge which has a headspace measurement of 1.775", however it will close (with some resistance) on a cartridge case sized to 1.774" headspace. So you can see it's about 0.001-0.002" from failing the Field gauge. (I tried to tighten up the headspace using the kit available from Springfield Sporters, but couldn't get the existing spacer block out of the reciever, but that's another story).

I was finding that unlubed, fired cases were actually LONGER than the measured headspace length of my rifle - how could that be? My theory was the cases were being stetched during extraction from the chamber. If so, it should be especially true if the cases are unlubed or the chamber was very dirty.

I recently fired some cartridges that were lightly lubed with a film of Rem-oil. I found that the fired cases were 0.003" shorter than unlubed cases. This supports my theory above and based on that, I think it's a GOOD THING to lube your ammunition for firing in the Ljungman.

In my testing, I've also found that even with the lubrication, the cases are stretched longer than the chamber headspace by about 0.003". The only cases I tested that didn't come out longer than the chamber are Remington cases, and they were unlubricated too. I think the reason is because the American manufactured cases have a smaller case head diameter and therefore are less prone to "sticking" in the chamber of the Ljungman. I would have to do more testing to prove that since Remington is the only "small head" case I tested.

Some average headspace measurements I've taken:

1.761" Unfired m/41 cartridge (87 / 070 headstamp)
1.768" Cases fired in bolt action rifles with "good" headspace (CG-63, Win. M70, M96 FSR)
1.775" Forster Field Headspace Gauge
1.778" Fired lubricated m/41 cartridges in my Ljungman
1.781" Fired unlubricated m/41 cartridges in my Ljungman

Sorry for the long-winded answer to your question. Hope that helps.

http://www.thehighroad.us/archive/index.php/t-402786.html

krochus
December 1st, 2008, 02:23 PM
Congratulations you bought the most obscure and cantankerous semiautomatic to learn loading for autoloaders on.


With the faster powders such as H335 I had shortstroking issues, I ended up with IMR4320 because it would short stroke with weak loads but would operate fine with near max loads, this told me I had arrived at the correct burn rate. Near max loads were required because at much below 2400fps a 140grn bullet would print almost a foot high. Remember the sights on these are fixed within a range so you're load will also have to shoot to the sights.

The problem with this particular rifle is unlike 223/308/30/06 or 7.62x39 you neither have specific semi auto data and you have a case that works best with completely ag42 unsuitable powders. Meaning that conventional 6.5x55 data is out the window for you.

My favorite is the "you have to lightly oil the rounds or the gun will rip the cases apart" comment.

I guess you're unaware then that the swedish always lubed the ammo for these rifles and the Swedish manuals go in depth to point this out.



http://www.surplusrifleforum.com/viewtopic.php?f=47&t=11436

OK, here we go. Lots of so called "experts" are going to jump on this. These rifles, the Jlungmans AG-42B types, were made to have the brass cases lubricated. I know this flies in the faces of many of our members who think they know better, but it is true. The Swedes used a very well made,semi-thick oil that was rubbed onto the loaded ammo to aid in extraction. As you know, the brass cases if left dry may or may not extract, tear in-half or get crushed in the action by that "killer" bolt.
I use a product that I have had very good luck with. Bordens " Slide-All" It is a dry film lube that seems to work very well. Now, my full house loads do not tear in-half. Extraction/ejection is normal ( if you call 25 yards normal) and accuracy has gone way up. Life of the fired brass so far is over 5 re-loads. I'm not too keen on sharing my loads as these rifles are very temperamental with hand loads. I do use a 140 grain bullet and a "medium ' port pressure type powder such as IMR-4895 and RELOADER-15. IMR-4350 and IMR 7828 shot well after I designed and installed a gas port valve. I like the sights on the rifle and how well the rifle handles. You can't bad mouth the rifles accuracy, that's for sure.
Here's a 200 meter target from last summer.

http://milsurpshooter.net/topic/37374

While the no-lube mantra is a safe and conventional approach, some of us have been using lubricated cases in military rifles for years with no problems. The operative principle seems to be that good rifle actions are built with enough strength to handle the full thrust of a lubed or wet cartridge (or an oily chamber) on a regular basis and do not actually depend on the relatively weak brass case to absorb any thrust. Makes sense to me - but it's not for everyone, especially those who are uncomfortable "thinking out of the box".

One example of a fairly lightweight locked-breech rifle action that prefers lubed cases is the AB42 Ljungman. If you think about it, another is the SVT-40, where gas lubrication is provided by a fluted chamber. It would be difficult to demonstrate that either of these tilting-block actions is inherently stronger than the Mosin.



http://pdf.textfiles.com/manuals/FIREARMS/ljungmann_ag_42b.pdf

 

[Bartholomew Roberts]

The greatest disadvantage of the system is that it is dirty. DI is a dirty system and blows residue directly into the mechanism.

People keep making this claim about DI impingement weapons and the AR15 in particular; but nobody seems to be able to actually show how the residue creates a real problem. And for that matter, DI isn't the only system that results in a ton of powder residue in the chamber - the roller lock system of the G3 and HK93 also create a similar, if not worse, mess out of the chamber and bolt, yet these systems are lauded as being the pinnacle of reliability.

If the problem is powder residue, then why does it work in the HK; but not the AR?

Here is a test of an M4 where the rifle has been completely stripped of all lubrication. The rifle fires 2,450 rounds without any lubrication before a stoppage occurs - and when it does occur, replacing the non-stock H3 buffer with a stock H buffer allows the rifle to go to 2,540 rounds.

So where is the evidence that fouling caused by DI is a realistic problem?

In my opinion, the problem with the DI system has nothing to do with powder residue - it is that the piston of a DI is an open system. You don't usually end up with sand or foreign debris in the piston chamber of a gas piston rifle because it is very difficult for foreign debris to enter those systems. In a DI weapon, the bolt carrier/bolt is also the piston chamber - which means that it is much more exposed to foreign debris. This is really where the Achilles heel of DI weapons lies - and look at how the Army handles dust environments - they do their best to seal the piston chamber (dust cover/muzzle caps/magwell blocked).

Powder residue is a red herring. You could run a DI weapon that fired absolutely clean; but I bet it would still be sensitive to foreign matter in the piston chamber.

Evolution has run its course, and DI is an evolutionary dead end.

I disagree. Whether the issue is powder residue as you contend or foreign debris, as I contend, it is pretty clear that the answer to the problem is lubrication. Test after test after test shows that the M4 runs well even when absolutely filthy so long as it is kept well lubricated.

Modern coatings that increase lubricity have the potential to make the DI design even more resistant to debris (powder or foreign). Not to mention the advantages you could gain in a DI system by actually designing a DI rifle around a 14.5" barrel instead of cutting down a 20" barrel and continuing to use the same components from the 20" rifle in the 14.5" rifle.

And, besides, it isn't exactly like the issue M4 is dust sensitive:

Those rifles just fired 6,000 rounds each with a 98.6% success rate (better than that if you believe Colt's version of the story.) If that is the "problem" we are trying to solve, we are still ahead of most of the rifles ever made.

This is not a problem for barracks troops with plenty of time on their hands, but for troops in the field, the high maintenance required to keep a DI system functioning is undesirable in a combat weapon.

Let's talk actual objective data. Please define for me the "high maintenance" necessary to keep a DI system functioning and what you consider to be an acceptable level of maintenance in a service weapon?

 

[Tirod]

Evolution has run its course, and DI is an evolutionary dead end.

Actually, evolution - if you subscribe to that concept - is still ongoing. It's more than DI, the control layout has influenced most new military designs since it's introduction. Safety, mag release, bolt hold open, and charging handle are now held to the minimum standard of being at least as good as Stoner's layout, or good justification given. Ergonomic control layout isn't haphazard or devil may care like previous curios and relics.

The barrel extension is now a serious design factor, as new guns come off the cad cam printer. The short multilug bolt engaging a short barrel extension has proved a sound basis for reducing significant amounts of weight, and is actually stronger. It's definitely part and parcel of increased accuracy, too. The Browning BLR and Savage bolt gun with barrel nut both share AR design concepts.

As for the tired DI concept, most who dislike it do so based on a flawed early fielding, not the design. It's a gas piston concept. It's in the bolt carrier, not out on the barrel, and cheaper to manufacture because of it. It also reduces the weight and number of operating parts. Mechanical efficiency isn't rated by making more complicated subsystems that drive up complexity and cost. It's about making things do more, and doing it more simply.

If there only seems to be one design out there, don't blame Stoner. That's a direct result of the constant and deliberate attempt by small minded gun makers to force their customers into buying proprietary parts from well controlled and highly profitable sources. If anything, the American consumer, and many others, are sick and tired of being hosed over maintenance and repair. 100 years of public exposure to automobiles, appliances, tools, and firearms designs beiing constantly churned to force owners to buy parts and repairs from authorized sources is now being confronted - the AR is very much the same from one to the other, despite the rollmark. We no longer have to be held hostage to a single source contract.

How is that a bad thing? Vendors who want to sell parts or assemblies now have to adhere to an international standard of design and construction. What they get is one they can upgrade in the future. That concept has been used by our Government, making A2's from M16 A nothings, and those can be converted into M4's. Not every 25 year old weapon in the inventory is a shot out, beat up mess.

If you want, we are now seeing the results of evolution - few other designs can economically or efficiently compete in the public market. Some may not like AR's and consider them the cockroach of the gun world, but when it comes down to it, they are everywhere and you can't kill them.

Better wake up, it's the future already.

 

[Slamfire]

And yet the Stoner platform is widely used across the world. Also, the notion that the weapon requires high maintenance is 100% false. Properly lubed it will run fine for longer than any engagements will last.

I knew many WWII veterans, worked with a few Korean War Veterans, personally know and have been squadded with a smattering of Vietnam Veterans, and know a surprising number of guys who have been deployed to the sandbox.

Pre M16 rifles, either short stroke piston Carbines, long stroke Garands, and the M14 gas expansion system, functioned after neglect and abuse. One Korean War Vet, unprompted, told me that no matter how dirty his Garand was, it always worked.

Many Vietnam Veterans have nothing good to say about the Stoner system. But all mention how often they had to clean the thing to keep it going. One Infantry Officer told me he made his men clean their weapons on every march break.

Gulf War Veterans, a USMC Reservist I was squadded with at Camp Perry, he told me they were cleaning their guns three times a day. At least in the dusty area of the South of Iraqi. Other veterans have mentioned similar cleaning cycles.

Molon, a poster on M4 Carbine wrote a “Ares Defense GSR-35: gas system retrofit range report
http://www.m4carbine.net/showthread.php?t=29052
If the pictures show, you can see just how much cleaner a gas piston system than a DI.

Now that the Government has the M4 TDP, Colt no longer has the strangle hold that it had over the Army. It is still a very strong political force, but now, with the total loss of its monopoly on the M16/M4 series of rifles, DI is heading towards the ash heap of history. The replacement for the American DI system will be a gas piston.

 

[Bartholomew Roberts]

Gulf War Veterans, a USMC Reservist I was squadded with at Camp Perry, he told me they were cleaning their guns three times a day.

When I was in boot camp, we had to clean our quarters (open bay barracks) twice a day; but I'm pretty sure that wasn't because it necessary for the barracks to function as designed.

Frankly, anybody who is remotely familar with the military system of small arms maintenance knows that there are problems there. Things like "white-glove" cleaning to satisfy officers/armorers. And of course, the zealous over-cleaning of rifles that are past their service life because nobody will remove the worn rifle/part from the system and so the servicemember ends up cleaning it 4 times a day like he is performing some voodoo ritual that will ward off the effects of his worn-out action spring and dead extractor.

In short, in my military experience, actual cleaning practices of the military rarely reflect what is necessary or even good practice.

If the pictures show, you can see just how much cleaner a gas piston system than a DI.

OK, it is cleaner; but what practical difference does it make?

ow that the Government has the M4 TDP, Colt no longer has the strangle hold that it had over the Army. It is still a very strong political force, but now, with the total loss of its monopoly on the M16/M4 series of rifles, DI is heading towards the ash heap of history.

I'm not following your reasoning here. It seems to me that if you are the Army and having been forced to buy your M4s from Colt at inflated prices for the past 20 years, then you are probably enjoying being able to get competitive bids on M4s. You are also probably not real excited about buying a new rifle (and new TDP) and being locked into that same situation for another 20 years.

If anything, the trend seems to be going the other way with SOCOM deprioritizing the Mk16 in favor of continuing to use the M4.

Realistically, the only thing that is likely to kill off DI is the LSAT cartridge.

 

[W L Johnson]

In short, in my military experience, actual cleaning practices of the military rarely reflect what is necessary or even good practice.

Armalite agrees with you
TECHNICAL NOTE 29: RIFLE CLEANING: http://www.armalite.com/images/Tech Notes\Tech Note 29, Rifle Cleaning, 99.04.pdf

From the link

Some of the worst cleaning practices are found among those expected to know best how to maintain rifles: the military. Especially in peacetime and in garrison locations, military procedures are too often focused not on cleaning properly, but on cleaning totally. That’s because of tradition and the sad fact that it’s hard to make a judgement call that a rifle is cleaned and preserved well enough for reliable service. It’s easier to say that there isn’t a speck of dirt remaining on the rifle.

Anyone with an AR-10/15 should read this link.

And another
TECHNICAL NOTE 54: DIRECT IMPINGEMENT VERSUS PISTON DRIVE
http://www.armalite.com/images/Tech Notes\Tech Note 54, Gas vs Op Rod Drive, 020815.pdf

Edit: There was site somewhere showing an AR-15 after 15,000 rds of wolf ammo without cleaning and it was still going.

 

[R.W.Dale]

I think all the rifle systems that use DI have been listed.

not yet

As best I can decide the Remington centerfire autoloaders 742/740/7400/750 are direct impingement. You have a short gas tube protruding from the gas block that acts directly on a long action bar attached directly to the bolt carrier

 

[68wj]

Armalite agrees with you
TECHNICAL NOTE 29: RIFLE CLEANING: http://www.armalite.com/images/Tech Notes\Tech Note 29, Rifle Cleaning, 99.04.pdf

As a former Marine armorer, I concur. The standards of cleanliness that I was instructed to uphold were absurd but attempting to do anything about it was even more futile. My last Ordnance Officer even agreed, but we were helpless to do anything about it.

Many rifles were stripped of their annodizing due to unauthorized solvents (electrical contact cleaner, carb cleaner, etc) or parts were broken due to improper techniques (unauthorized disassembly, using firing pins as carbon scrapers, etc). All this was done to achieve the perfectly clean weapon. Non-DI weapons were also victim to these practices. All that, and a week later, the required light film of CLP would draw more carbon out of the metal and create a "dirty" gun while just sitting in the rack.

 

[Ithaca37]

I knew many WWII veterans, worked with a few Korean War Veterans, personally know and have been squadded with a smattering of Vietnam Veterans, and know a surprising number of guys who have been deployed to the sandbox.

Pre M16 rifles, either short stroke piston Carbines, long stroke Garands, and the M14 gas expansion system, functioned after neglect and abuse. One Korean War Vet, unprompted, told me that no matter how dirty his Garand was, it always worked.

Many Vietnam Veterans have nothing good to say about the Stoner system. But all mention how often they had to clean the thing to keep it going. One Infantry Officer told me he made his men clean their weapons on every march break.

Gulf War Veterans, a USMC Reservist I was squadded with at Camp Perry, he told me they were cleaning their guns three times a day. At least in the dusty area of the South of Iraqi. Other veterans have mentioned similar cleaning cycles.

Well, the veterans I know report no issues with the M4s they used in the sandbox. Anecdotal stories are meaningless. What matters is testing and data. Testing has shown that the Stoner platform is reliable in adverse conditions. As noted in a post above, testing has shown the weapons capable of firing thousands of round without failures.

 

[Bartholomew Roberts]

All that, and a week later, the required light film of CLP would draw more carbon out of the metal and create a "dirty" gun while just sitting in the rack.

Yup, that is exactly it. I can remember using unauthorized solvents to strip/degrease the rifle and then being told not to apply CLP to it before turning it back in because it would just create a greasy grey smudge that would get the rifle rejected.

So the rifle goes back into storage with no corrosion protection. Springs and parts rust. Rifle starts to malfunction. Why is it malfunctioning? Must not be clean enough! Let's clean rifles even more brutally than we did last time.

This whole mythology that the M16 family of weapons needs to be spotlessly clean is probably responsible for half of the anecdotal problems regarding the M16.

 

[451 Detonics]

DI and short barrel, this is supposed to be a cleaning disaster yet this one has run over 2500 rounds between cleanings with zero malfunctions...the system works great. I see no reason to add more easily damaged parts that have to be cleaned to the equation...cleaning the gas tube is a breeze...a couple squirts of carb cleaner does a great job, even on my Hakim which is fed corrosive ammo.

Mobil 1 is my preferred lubricant btw...

 

[Robert]

I can remember using unauthorized solvents to strip/degrease the rifle and then being told not to apply CLP to it before turning it back in because it would just create a greasy grey smudge that would get the rifle rejected.

Yeah I have never used Brake Cleaner to clean an M16 because I knew that any amount of residue meant I'd be cleaning the damn thing again.