Talk:Direct impingement

Current GIF Images
I'm fairly certain that the animated .gif images on this page are specifically used to advertise against a Direct Impingement system so people would purchase that company's piston conversion systems. I feel that they should not be used in their current state on this page. Reefstiz (talk) 03:40, 2 February 2012 (UTC)

The animations accurately reflect the contents of the article and there are no advertisements or company names of any type contained within the animations. Also, the animations are simply labeled "M4 Carbine direct impingement gas system" and "H&K 416 short-stroke gas piston" to reflect the contents of the article. I don't see any problems here. — Preceding unsigned comment added by 71.22.156.40 (talk) 08:09, 2 February 2012 (UTC)

I agree. The animations currently grossly misrepresent the facts and have no credible sources supporting them They should be removed, or replaced with more accurate images. — Preceding unsigned comment added by 2600:8807:106:3D00:2470:D3AC:A68C:AAD (talk) 03:08, 24 February 2017 (UTC)

Misidentified?
Direct Impingment refers to a gas system in which the gas from the bore acts directly on the piston face - with no expansion chamber. The FAL rifle and the AK-47 are classified by weapon engineers and professional armourers as Direct Impingment.

The Bleed-off and Expansion system used by the M16 family of weapons is often refered to in marketing information as a Direct Gas system resulting in some confusion. The gas is allowed to expand in a pressure vessel that includes the gas tube and the expansion area in the bolt. Excess gas is then bled off through gas vents located on the side of the bolt carrier and also when the gas tube separates from the gas key.

By comparison an FN Minimi used an Expansion system due to the small cup on the piston that allows for some gas expansion where other long stroke pistons have no expansion space and are thus refered to as Direct Imopingement.

The M60 machine gun uses an Expansion and Cut-off system where the gas expands in the regulator and when the piston cup moves the gas hole is closed off cutting off the flow of gas.

I will post the text book references shortly. Cheers, Colt Armourer 00:57, 17 January 2007 (UTC)


 * You're incorrect. There is a piston face on EVERY gas operated firearm in existence.  There is, by definition, also an expansion chamber.  True, the FIRST Browning machinegun had a 'flapper'that utilized the expanding high-pressure gas after it exhausted into the air (as with the 'gas trap' variety of operating systems, but all of these are obsolete.  This piston face can be in-line with the barrel as are the vast majority of them (the Colt Potato digger is an exception) but the BASIC operating principle of any gas operated weapon is that gas operates on a surface moving that surface.
 * Direct Impingement Means that this gas operates DIRECTLY on the bolt and bolt carrier rather than through a piston rod, extension, or other such mechanical connecting rod. The AK-47 is interesting in that the piston rod is a functional part of the bolt carrier being affixed albiet loosely sometimes.  The FAL, however, is different in that the piston rod is not attached to the bolt carrier. There are variations... The HK G36 utilizes a conical surface with a 'nipple' in the middle.  The Bang system utilizes a gas trap at the muzzle and a ring shaped 'piston'.  There are many variations.  The furthest from 'direct' one can cite is, I believe, the Colt Potato digger which utilizes a series of levers to operate the action.  Not sure what armorers call such things... I'm a student of the gun, not a mechanic. --Asams10 05:11, 17 January 2007 (UTC)

The Stoner system, as described by Eugene Stoner himself in the patent application as "This invention is a true expanding gas system rather than the conventional impinging system" In other words, while a M1 uses gas directly pressing on a piston, and a MAS-49 or Ljungman uses gas directly striking the bolt carrier to effect movement, Stoner by his own definition and his own patent application specifically states that this is a gas expansion system using a piston and cylinder. Thus the Stoner system and derivatives cannot be called a "Direct Impingement" system, no matter how many people may refer to it. It is simply wrong to call an M-16 a "Direct Impingement" system.

As well as Mr. Stoner's own words, lets look at the dictionary for a second: Direct: 14. proceeding in a straight line or by the shortest course; straight; undeviating; not oblique: a direct route.

Impingement: The noun form of Impinge, defined as: 3. to strike; dash; collide

So to strike in a straight line or the shortest course defines the AG42 or the MAS-49, but has no bearing on the M-16. Gases striking the bolt carrier key have no effect upon the opening of the bolt. It is only after the gases have turned and been redirected (violating the definition of direct) that they expand upon the back of the bolt head and force the bolt carrier backwards.

Please respect the common use of wiki and do not cause personal attacks or edit wars in order to prove your point. An M-16 plainly and simply is not a direct impingement weapon. Thank you. —Preceding unsigned comment added by 84.167.82.27 (talk) 01:21, 18 October 2008 (UTC)


 * You're citing the patent, eh? So, what surface moves when the gas expands?  Do tell.  What part of the gun is being pushed by this impingement?  By the way, ignorant is not a personal attack, it's a fact.  You are ignorant of the facts.  You will learn by the numbers, recruit.  I will teach you. --Nukes4Tots (talk) 01:45, 18 October 2008 (UTC)

Sigh. Once again you stoop to personal attacks and an assumed superiority in the absence of facts. I will now explain basic physics to you since the actual patent drawings from the man who invented the system aren't enough to convince you that you are wrong.

Direct impingement uses the kinetic energy of moving gas particles to hit the bolt carrier directly and move the bolt carrier back.

Gas Expansion relies on the thermal expansion of the gasses (not the same as kinetic energy) to expoand within the cylinder to open the bolt carrier.

Once again, gas particles striking the bolt carrier key and from the gas tube do not open the bolt with kinetic energy. That is why it is not Direct Impingement.

As for your comment on the edits page about sources, here are a couple:

1) MAS49 and 49/56: Rifles with La Difference; Paul Scarlata, Shotgun News Treasury, Page 58-59

"The MAS Mle. 1928 used a direct impingement gas system wherein a simple tube placed on top of the barrel carried powder gas to the rear, where it IMPINGED DIRECTLY ON THE BOLT CARRIER DOING AWAY WITH PISTONS, SPRINGS SEALS AND QUITE A BIT OF TIME CONSUMING MACHINING" (emphasis mine) If you look at the M-16, you see a precision machined piston (bolt head) with seals (the rings) and a precision machined cylinder, the bolt carrier. THe gas in the M-16 does not strike the bolt carrier, it expands inside the cylinder against the piston. By definition and by art, the M-16 is not a direct impingement system.

2) Technical Manual, Maintenance, U.S. Rifle Garand Caliber .30 M1, Beretta Arms Company, Brescia, Italy, Page 14:

"As the bullet passes over the gas port drilled in the under side of the barrel, some of the gas escapes into the cylinder and blasts back against the piston and operating rod with strength enough to drive the rod to the rear and compress the return spring" This is an example of how a "regular" gas system works, but here we are STILL talking about gas kinetic energy pushing the piston, not EXPANSION of gas within something.

Now that I have shown you (I hope clearly) what the AR-10/AR-15/M-16 is NOT, here is another desctription of what it IS:

3) The AR-15 Complete Owner's Guide, Walt Kuleck and Scott Duff, Page 117 "As the bullet passes by the gas port in the top of the barrel(covered by the front sight base or gas block), hot gas is allowed to pass through the port, into the front sight post or gas block, and thence into the gas tube. The gas flows down the gas tube towards the upper receiver, where it continues into the carrier key on top of the bolt carrier.  The carrier key's inside diameter is slightly larger than the gas tube's outside diameter, thus the key envelopes the gas tube and overlaps it by about 1/2 inch.  The gas FLOWS DOWN THE KEY INTO THE BOLT CARRIER, WHICH IS FORCED REARWARD BY THE PRESSURE OF THE GAS WITHIN" (emphasis mine) Simply put, the gas expands in the bolt carrier, using thermal energy to effect the work.

4) Small Arms of the World, 12th edition, Edward Clinton Ezell On Page 47, the author refers to the M-16 thusly "A tube-type gas system was employed to convey the gas from a port under the front sight, along the top of the barrel, and into a space in the bolt carrier assembly" No mention of direct impingement. However, for the MAS 49, on Page 440, he states ""the gas blows directly back through the gas tube directly into a hole in the top face of the bolt carrier".  Similarly for the AG42, on Page 664, "The gas is directed back through the gas cylinder (meaning tube, in this case, comment mine) WHERE IT IMPINGES UPON AN EXTENSION OF THE BOLT CARRIER... (emphasis mine) The gas thus DELIVERS ITS THRUST DIRECTLY TO THE FACE OF THE BOLT CARRIER ITSELF" (emphasis mine).

So you have a world expert in the field of firearms correctly and accurately describing the MAS-49 and AG42 for what they are, direct impingement, and accurately describing the M-16 as using gas expanding into a space within the bolt carrier. If your credentials are sufficient, might I suggest that you "Teach" Mr. Ezell?

To convert your AR-15 to direct impingement, (if you have one, assuming that you are old enough to own firearms and meet the regulatory requirements in your area) I suggest this:

1) Remove your bolt carrier key. 2) Weld the gas port at the bottom of the key shut so that no gas can flow down into the carrier itself. 3) Reinstall the key 4) Test fire, if you feel safe doing so.

You will undoubtedly find that with the gas having only the key to work on, that if you try to use direct impingement like a MAS-49, Ljungman or Hakim, that the weapon will not function correctly.

I will grant you that many gun writers refer to Stoner's design as direct impingement, or take a shortcut and simply say that the gas strikes the bolt carrier. They are either oversimplifying or simply do not understand how it works. Simply repeating an incorrect statement does not make it true, no how many times you do so. Copernicus postulated a heliocentric solar system, Kepler refined the orbits into ellipses, and yet the Catholic Church imprisoned Galileo in the Galileo_affair because they believed that the Earth, not the sun was the center not only of the solar system but of the universe. Just because millions of people believe something does not make it right.

So, I have now given you authoritative sources of what gas expansion systems are, by no less authorities than the man who designed it himself (Stoner's Patent) and Ezell. I have also given you examples of what Direct Impingement is (the point of the article) and how it differs from basic piston arrangements.

Please stop trolling this site and undoing the changes of others. Wikis are about sharing, not posturing and insults.

Thanks —Preceding unsigned comment added by 84.167.82.27 (talk) 12:23, 18 October 2008 (UTC)


 * Listen person who ignores the facts, You can read and write all you want, but you didn't answer the one question that I asked. Where does the gas impinge?  I've read Stoners Patnet.  The difference between you and I is a level of comprehension.  All gas operated systems impinge.  Stoners Patent says that it impinges on the bolt carrier.  Uh, how much simpler do you want it to be?  Please stop characterizing my use of the words Ignorant, Ignore, and Ignorance as personal attacks and read the actual meaning of them.  If you're taking it the wrong way, that'd be right along the lines of your interpretation of the patent. Please cite a source, again, that says that Stoner's system is not direct impingement. --Nukes4Tots (talk) 13:25, 18 October 2008 (UTC)

Um, let me once again be polite in my answer and walk you through this.

1) As for your question on where the gas impinges, well, that's the POINT I am trying to make: It doesn't.  Gas des not strike anything in the M-16 system.  It expands in the bolt carrier, as I and several others have already described.  Please read my points again about modification of a carrier key to illustrate.

2) As for the source that says the Stoner designed system is not direct impingement, Um, take a look at points 3 and 4 above, which state directly that. Or perhaps read Mr. Stoner's patent itself (this is not the first time I have suggested that you do so, and I have quoted it above).  Please find for me ANYWHERE where Eugene Stoner describes his system as direct impingement?  For that matter, find an authoritative source who states that it is?  Paragraph page and book please.   Gun magazines don't count for the most part, they are paid by the word and tend to reprint what others say w/o much authority.  I am talking about a real, acknowledged researcher on the level of Ezell.  A verifiable source.  You have given none to my knowledge.

3) Why are you not able to understand such a simple comment that gas blowing against the front of a solid chunk of metal (thus, Direct Impingement) is Not/Not the same as gas flowing into a cylinder and expanding a piston (sealed with rings, like a car) in said cylinder? Not at all the same.

4) I would suggest that you stop taking this personally and allow yourself to admit that the M-16 is not an example of Direct Impingement, and move on. It takes courage to admit a mistake, while casting aspersions at others does not.

5) Finally, "Ignorant" as used by you in your comments is offensive, as are such phrases as "let me teach you", "recruit" "vandal" and "Person who ignores the facts" etc. Its obvious by your response time that you sit on this topic and wait to be challenged.  Its also obvious by your profile that you are a argumentative person.  None of this is in the wiki spirit.  It is about sharing and spreading knowledge, not standing atop a lonely hill and proclaiming yourself the god of the page.  its just the Internet, there is plenty out there that is wrong.


 * Closed-minded one, you seem to be misinterpreting what you read. Once again, I'll challenge you to provide a source that states in some substantive form that Direct impingement does not acceptably describe the Stoner system.  If you cannot, please go away. Please provide the source like this, "Joe-Bob Freebird says on page 17 of his book entitled 'Gas Operation for Dummies' that the M16 does not operate on the direct impingement principle." --Nukes4Tots (talk) 20:34, 20 October 2008 (UTC)

The article states that 'the gas cylinder acts as a piston' which is surely not correct, is it? A piston operates within a cylinder in my book. 92.30.43.100 (talk) 12:04, 6 November 2010 (UTC)

I may be resurrecting an old debate, but whatever. It seems to me that whether the gun gas actually directly impinges (as per the given defintion) on the bolt carrier or expands (as has been asserted) it is effective to say that direct impingment gas operation is simply an elimination of the piston for simplicity's sake. Furthermore, from a physics standpoint, isn't it accurate that in a sealed system (expansion chamber in bolt carrier) the pressure that drives the expansion of gases is because of those particles' kinetic energy? Not a scientist, just like firearms. — Preceding unsigned comment added by 71.245.163.20 (talk) 23:51, 20 May 2013 (UTC)

I agree with the preceding contributor. My understanding is that all gas operated firearms utilize gas expanding in a closed system. Said gas is being rapidly produced by the cumbustion of solid propellant, so it may not be all, or even predominantly, thermal expansion. That being the case, the use of expanding gasses cannot be the basis of distinction between "direct impingement" actions and other types of gas operated actions.[dstjohn70] — Preceding unsigned comment added by Dstjohn70 (talk • contribs) 06:41, 29 August 2013 (UTC)

Swedish Rilfe
Could somebody please find a way to integrate this smoothly into the text? "The Swedish AG-42 Ljungman, used a simplified direct-impingement operating system." --Nukes4Tots (talk) 16:33, 7 September 2008 (UTC)

Undue weight
This article seems to be a perfect example of undue weight to disparage DI rifles. There are 2 padded out paragraphs criticizing DI rifles that are filled with editorializing and weasel words. There are a lot of redundancies and poor writing. Those two paragraphs could easily be combined into one and shortened considerably.

Jamescart (talk) 06:05, 28 May 2016 (UTC)

Lighter Than What?
It is a simple illiteracy to say that A is lighter. In the English language something has to be lighter than something else. This article fails that test. David Lloyd-Jones (talk) 19:37, 2 November 2016 (UTC)

Suggesting merge into Action (firearms)
This is an Action (firearms) topic and should be merged with that or deleted. Digitallymade (talk) 12:27, 3 March 2017 (UTC)
 * Strong oppose, it requires a summary section at Action (firearms) but rates its own article.--Mike - Μολὼν λαβέ 17:20, 3 March 2017 (UTC)
 * Oppose, the main article link in the Action (firearms) article appropriately allows interested readers to access this information without bloating the broader article to an unwieldy size. Thewellman (talk) 18:44, 9 August 2021 (UTC)