Talk:Gas-operated reloading

Requested move

Rename to conform to naming conventions of case and nouns/adjectives.

---

Add *Support or *Oppose followed by an optional one sentence explanation, then sign your vote with ~~~~

Proposed name change

Isn't there supposed to be something here about proposed name change to Gas operation?

I figured it was non-controversial and didn't need discussion. Apologies. Added now. -Ethan0 19:19, 21 October 2005 (UTC)

That sounds like a medical procedure to reduce burping to me.

I'd suggest gas-operated reloading instead. Gene Nygaard 22:14, 20 October 2005 (UTC)

Even more problematic, gas operation suggests to me a secondary recovery procedure in oil and gas extraction, or possibly most any pneumatic device, maybe a jackhammer or dentist's drill or whatever. It's just too cryptic. Only a few of the Google hits for the phrase "gas operation" deal with firearms. Gene Nygaard 22:21, 20 October 2005 (UTC)

I suggested "Gas operation" to be consistent with Recoil operation. Seems like if one is changed so should the other, perhaps. Though there are others (Blowback (arms); Gas-delayed blowback) as well that aren't particularly consistent. Seems like these could stand to be updated, along with Firearm action (which doesn't even currently link to the main articles on the systems - I'll work on that). Maybe "Gas action"? -Ethan0 19:19, 21 October 2005 (UTC)

Second Gene Nygaard's suggestion. Gas-operated has far too wide a range of meanings. Rd232 22:39, 20 October 2005 (UTC)

I agree, and to be precise, it should be "Gas-operated reloading", without "Operated" capitalized as it currently is. 24.30.66.41 15:37, 2 December 2005 (UTC)

Request not fulfilled due to lack of consensus. Rob Church ^Talk 20:38, 4 November 2005 (UTC)

But there was consensus that the current name of the article isn't what it should be. How would I go about re-opening a requested move discussion? Just newly add it to WP:RM, or what? Ethan0 19:18, 5 November 2005 (UTC)

It is not a matter of opinion; look up and reference any military manuals on the type of operation their weapons have. Gas-Operated is one of those types. This is why I created this page in the first place. I fail to see what else "Gas-Operated" implies, and how this could lead to confusion with other subjects and have 'far too wide a range of meanings' unless someone is not familiar with fiearms, then in which case it makes it even worse to change a page because of lack of experience and familiarization. "Recoil Operation" should be changed to "Recoil-Operated" and so on and so forth. "Gas-Operated Reloading" is beyond redundant, and action in a firearm is determined by how the bolt is worked. I vote no. 66.47.50.214 08:49, 21 November 2005 (UTC) Brenden

Image needs legend

The current image labels six components but they are not explained in either the text or the caption. It's kind of jarring. I suggest that they be labelled in the caption. -- Mike Wilson 04:16, 23 December 2005 (UTC)

Cool. I think it's better. -- Mike Wilson 07:49, 23 December 2005 (UTC)

Thx. :) --shotgunlee 08:34, 23 December 2005 (UTC)

Inaccurate Definitions

The definition of short stroke and long stroke gas operation are incorrect, implying that the time duration that the piston is subjected to the gas determines the type of gas operation. This is a revisionist definition that has never been included in any manuals or reference books I'm aware of. In fact, one of the footnotes [3] relies on the bore x stroke of an automotive engine. !! Indeed, the impetus duration or either so-called long or short stroke gas operation is probably about the same, it is whether or not the piston makes the entire journey the bolt carrier group does.

In a firearm application, a long stroke piston is attached to the bolt carrier and makes the complete trip back and forth with the bolt carrier. Examples are AK-47 and BAR M1918;

Short stroke refers to a separate piston that moves only a short distance, imparting a motion to the bolt carrier which continues its work leaving the piston at the end of its travel. M1 Carbine, M14, SVD Dragunov, M60 Machine gun all are examples of short stroke pistons.

The M1 Garand is an archaic example that could almost be called a separate type of operation which I would propose to call "long impetus" gas operated reloading. It is archaic and was abandoned as unnecessarily fussy and complicated; it required special ammunition that operated within a narrow band of pressure to avoid wrecking the system. Even the derivative US Rifle, M14 used the short stroke piston.

Your understanding of the operation of a piston is incorrect as are numerous descriptions in the gun world. Short-stroke and long-stroke pistons operate differently in firearms as they do in internal combustion engines. Due to the fairly small sample size of firearm pistons vs. internal combustion engines, it might seem simple to use arbitrary distinctions to describe short vs. long stroke, however the bottom line is that an AR-18 and AK-47 piston operate IDENTICALLY. Now, what happens AFTER the power stroke differs in the way you described, however this is not the 'stroke' of the piston. Read Hatcher's Notebook before you continue to argue your point.--Asams10 03:48, 15 April 2007 (UTC)

From how I am reading it, Hatcher's Notebook references D.M. Williams as the patented inventor of the short-stroke gas piston, and both Hatcher's and the patent indicate the piston being limited in its travel as the defining characteristic of the short stroke system-

The Short-Stroke Gas Piston (pg 67, Hatcher's Notebook)

"...the short stroke piston principle, patented by Mr. David M. Williams. The gas is taken of near the breech, where the pressure is very high. The piston is completely housed in the cylinder, and is permitted to move through a stroke of only about a tenth of an inch. At the rear of it's stroke, it acts as a valve, and prevents the gas from escaping from the gas cylinder except by going back into the barrel through the port by which it entered the gas cylinder.

The operating slide rests against the projecting end of the piston, which, under the impact of the gas, strikes the operating slide a sharp blow.Even the short piston stroke imparts to the operating slide sufficient energy to cause it to carry through and operate the mechanisim.

It is something like the action of a croquet ball held under the foot and struck a sharp blow with a mallet while another ball rests freely against the far side. The second ball will be driven swiftly away by the elastic impact.

This system has the great advantage of doing away with the long operationg rod..."

U.S. patent 2,090,656 by D.M Williams

"In it's broadest form, applicants invention comprises the combination in a repeating firearm of a barrel member and slide member being reciprocable one with respect to the other to move between approximal and spaced positions, a vibrator [piston assembly] arranged to engage one of said members and initiate movement of the members to spaced postion... As pointed out, the vibrator is mounted for limited reciprocation."3000fps (talk) 16:36, 30 June 2008 (UTC)

Hope you're not citing that patent, because you're way off. This is the patent for the Floating Chamber operation, not for the piston. Check your sources better. Short-stroke and long-stroke are determined by the point in the barrel at which the gas is tapped and the time under pressure of the piston head. I'll have to say, you gave it a good college try. Please come again. The Hatcher quote is taken out of context, BTW, but I've had enough already. --'''I am Asamuel''' (talk) 17:03, 30 June 2008 (UTC)

Yes, I am citing the patent. If the patent cited were only for the floating chamber, please explain figure 12a, which clearly shows gas tapped forward of a non-floating chamber and acting upon a piston below? The patent is for the piston, it's part of the system. The floating chamber acts as the piston in that circumstance, figure 12a (page 5) makes that clear. The Hatcher quote is not out of context, it is word-for-word the section titled "The Short-Stroke Gas Piston" of chapter four, Automatic Gun Mechanisms.3000fps (talk) 18:02, 30 June 2008 (UTC)

I'm inclined to believe that you are trolling, so here's some more food. Here's the full quote that you so conveniently didn't place as you thought it'd support your opinion if you took it out of context, "In 1940 the Winchester Repeating Arms Co. submitted for test a 9 1/2 pound Cal. 30 semiautomatic rifle operating on the short stroke piston principle, patented by Mr. David M. Williams." The next paragraph describes WHERE IN THE BARREL the gas is tapped and HOW LOONG the stroke is (1/10th of an inch in this case). The rifle was patented by David M. Williams. The particular tappet-style short-stroke piston devised by David M. Williams was patented. There were at least half a dozen short-stroke rifles on the market at the time Williams was still obsessed with the floating chamber. Williams was a braggart and a brilliant designer, but he did not develop THE short-stroke principle though he developed one of the best. --'''I am Asamuel''' (talk) 18:26, 30 June 2008 (UTC)

Not trolling at all, just trying to find the truth. Above, you listed Hatcher as a source, so I thought I'd look into it and I'm relaying what I found. The part you've quoted (which I quoted as well, BTW) which describes distance of travel and port placement is a small part of the section, with nothing about bore/stroke or dwell. No, the remainder of the entire section on the short-stroke gas piston is devoted to explaining the piston being limited in its travel (which the 1/10" could be interpreted as supporting) and acting upon a separate operating slide mechanism. The section is devoted to the short-stroke piston, using the M1 carbine as example. If Hatcher is to be used as a source for what a short or long stroke gas system is than wouldn't he have mentioned bore/stroke and dwell, if the definition were correct? Or should we discount Hatcher altogether? Also, if where the barrel is tapped (close to the chamber being considered short-stroke), why is the AK (as well as most other military piston driven rifles) considered short stroke when the barrel is tapped closer to the muzzle than the chamber?3000fps (talk) 19:01, 30 June 2008 (UTC)

Hatcher was not defining the short-stroke piston. At the time, most mechanisms (Garand, Bang, BAR, etc) were true long-stroke pistons. The limiting factor was not that gas could not be tapped at the rear of the barrel but that it would beat the shit out of the mechanism if it were. While the BAR mechanism was long stroke, the operating parts were significantly heavy enough to allow gas to be tapped further down the barrel. By tapping gas closer to the bore, it operated cleaner but gave much too much power for a small rifle to operate. This problem was solved with numerous SHORT-STROKE systems. They took several approaches to the problem of how to reliably limit the travel of the piston and time under pressure. Engineers at the time were quite concerned with the kinetics of how the system worked and perfecting them.

While Williams used the approach of having the piston stop after a SHORT STROKE, work on the Garand concentrated on a 'gas cutoff' system where the piston would move and cut the flow of gas off after a SHORT STROKE. Still others used a vent system where there were ports (SKS) or slots (AK-47). If you look at the AK, the gas goes AROUND the piston once it's gone back a short distance. This is no longer the power stroke, the piston is simply along for the ride, unlike the Garand where the piston is under pressure a LONG time.

As I've said before, most 'gun people' don't understand the basic concepts. They see the Garand and assume that long stroke means the piston is attached to the bolt carrier. It's a common mistake, but a mistake nonetheless. The proper terminology is that the piston is affixed to the bolt carrier and travels with it the whole way. As I've said before, the "STROKE" part of the operating cycle is functionaly equivelant for both the AR-18 (often described as the quintessential short-stroke) and the AK-47. The stroke of the Carbine and SCAR is actually shorter still because these are the 'tappet' variety of short-stroke piston. The tappet design, for me, is the most elegant of various solutions as it allows for a truly short distance from chamber to port and correspondingly cleaner gas system that does not vent into the atmosphere. It's cleaner, lighter, and cheaper, but it is only one of a dozen varieties of short stroke piston. Calling it a 'tappet' system is the best way to describe it. In defense of my position, Hatcher was writing the book as the gas cutoff system was just beind developed and vent systems were known, but not well known in the west. --'''I am Asamuel''' (talk) 20:35, 30 June 2008 (UTC)

It seems to me that this whole discussion turns on the use of the mechanical engineering term "stroke". I'm not a mech engineer, but I'll do the best I can. From what I can tell one group (the AK47 = long stroke group) takes stroke in it's standard definition as "the distance the piston travels". This definition is applied normally to engines, but it seems reasonable that designers of autoloading firearms ~60-100 years ago would have used the term in the common way (that is, if they bothered to define stroke at all, much less to differentiate between short and long). The other group (AK47 = short stroke) seems to use the term stroke to mean, more specifically, "power stroke". In an engine the power stroke is the piston's movement under pressure from combustion. I don't know if there are any engine designs that use a short-swift combustion pressure that leaves the rest to momentum (the way an AR-18 does), so I'm not sure if there's ever been a need to define power stroke as either distance of movement under pressure only or distance of movement under pressure and resulting momentum (equivalent to total movement of the piston), as they may be the same thing (distance) in most applications. If engines do not usually/ever have an AR-18 style power stroke, then the AK47 = short stroke group seems to be using the terminology of stroke in a way that is exclusive to firearms. This may very well be the case, too. I don't know the right answer, but I would love to see it demonstrated/explained why one definition or the other is correct, or why firearms use a definition separate from the rest of mechanical engineering.CrunchRiff (talk) 03:06, 8 July 2008 (UTC)

You make some good points, but your analogy is flawed. In a long-stroke engine, the length of the stroke is used for things other than power. It is used for exhaust and compression. In a firearm, there is ZERO functional difference in the stroke of an AK-47 and an AR-18. There is a design difference in whether or not the piston is firmly fixed to the bolt carrier, but that is a red herring. It means nothing. When the history of gas-operated weapons is examined, much emphasis was given to the problem of how to deal with 'too much power' being that gas pressure would beat the heck out of the operating mechanism. The first gas-operated weapons had no issues tapping high-pressure gas as this gas was operating a HUGE breechblock (potato digger). Now, when lighter firearms came into use such as the Bang Rifle and Garand, the problem was solved by tapping the gas at or near the muzzle. This resulted in less gas that needed to operate over a long period of time. These systems were unvented and gas operated on the piston the entire length of the stroke. Near the end of the stroke, gas pressure has dropped to near ambient. The problem with these systems is weight and complexity. The solutions involved the tappet (M1 Carbine), expansion and cutoff (M14 Rifle), and venting through holes as in the SKS or through longitudinal slots as on the AK-47. These systems allowed high-pressure gas to act on the piston for shorter periods of time therefore they would not heat the gas parts excessively or provide too much energy to working parts. The gun could be made with a shorter barrel and the gas system parts were lighter and simpler to manufacture. This was all due to limiting the stroke length of the piston and making it shorter. Historically, the term short-stroke was first applied AFAIK to the M-1 Carbine. It's defining characteristic was its short stroke that was looked upon as a breakthrough at the time. The M1 Garand was modified with an M1 Carbine style gas system at one time. This fell out of favor as the 'more advanced' M14 style gas cutoff was thought to deal with Corrosive ammo better. It's notable that the M1 Carbine required non-corrosive ammo whereas the M1 Garand shot corrosive ammo until 1950 I believe.

Where all the confusion lies is in the similarity in the Garand and AK-47's gas systems. Both pistons are affixed to the operating rods/carriers. This leads to the mistaken assumption that they operate in the same manner. Further confusing the situation is the fact that the original AK-47 (not the AKM) had no vent slots at the end of the power stroke. The Piston merely opened up into a guide tube with corrugated depressions. Gas vents around the piston and back towards the action. There are holes further down the tube to vent the gas and keep it from excessively blowing debris back. You'll note that after firing an AK of the old variety there is a great deal of carbon built up behind the piston on the piston rod. The AKM is much cleaner. Examining the 'quintessential' short-stroke (the AR-18), gas is vented through two holes and the energy of the piston moving is imparted to the bolt carrier through transfer from the tappet rod. But the problem is, that's the same way on the AK-47. The difference is the AK-47 DRAGS the piston and piston rod with it through the rest of the stroke. It doesn't need to. The FAL and SKS demonstrate this. It does this to make the gun simpler, but it doesn't change the BASIC functioning of the stroke. --'''I am Asamuel''' (talk) 13:36, 8 July 2008 (UTC)

So you're indicating that the AK = long stroke group argues their point not from any understanding of engineerings terms (where stroke = length of piston travel), but just because both the AK and the Garand, a known long-stroke design, have pistons attached to carriers regardless of the fact that they operate differently? —Preceding unsigned comment added by CrunchRiff (talk • contribs) 21:26, 8 July 2008 (UTC)

The definitions are clear -- and have been for decades. If the gas piston moves the entire length of the operating stroke of teh bolt carrier, it is a long stroke gas system. If the piston moves LESS THAN the distance of the operating stroke, it is a short stroke. It is irrelevant whether or not the piston is attached -- although the piston of a short stroke system cannot be attached to the carrier. Definitions deriving from internal combustion engines are absolutely irrelevant and inapplicable.

The Kalashnikov action DOES NOT merely "drag" the piston along -- the mass of the piston provides momemtum to carry the action parts back.

If all gas operation systems involving pistons are "short stroke" merely becuase the system vents excess gas, then you have just stated that ALL gas operating systems are, by your definition, "short stroke". You see, the OTHER part of the gas system that provides the other end of teh sealant is THE BULLET -- once it leaves the barrel, the excess pressure vents out the (relatively large) hole in the front called THE MUZZLE. There is still high pressure gas in the AK gas tube when the piston passes the vent holes -- they just reduce it a little, but the pressure drops to near ambient once the bullet leaves the bore. And ALL before the action has unlocked the bolt. It doesn;t matter if it is long-stroke, short-stroke, direct gas impingement, or operates by Pure Friggin' Magic -- once the bullet leaves the bore, the "excess" gas is bled off anyway, and this is ALWAYS before teh action has unlocked. —Preceding unsigned comment added by Geodkyt (talk • contribs) 20:27, 24 July 2008 (UTC)

So according to your statement, the AK and the Garand piston operations are called the same (long-stroke) despite their differences in design?

I don't remember anyone proposing a definition based purely on the concept of venting. The "AK = Short Stroke" argument is not that it is short stroke simply because the gas is vented. The argument is that once the piston head passes the vent holes, the gas does not continue to exert enough force on the piston to accelerate the operating group. Rather, by that time the gas has already accelerated the action enough that the mass of the moving parts continues to move primarily because of momentum. Though I'm not as familiar with the gas cut-off system found in the M14, it sounds like illustration enough to show the "Short Stroke = AK" club does not arrive at their defintion purely because of venting.

What is the benefit of having vent holes in the AK? You say it reduces pressure "a little". What does this achieve if it doesn't matter until the bullet leaves the barrel? And just so I know ('cause I'm learning this stuff too, hence all these gadfly questions), where do you go to learn how long the bullet is in the barrel vs how long there's high-pressure gas in the gas tube; the change in gas pressure in the gas tube over time; etc... I ask because it sounds like you know.CrunchRiff (talk) 23:04, 24 July 2008 (UTC)

Lever operation

This section is under dispute, with the claim that the lever operation is equivalent to a short stroke action:

Lever operation

The earliest successful gas operating mechanism appeared in the M1895 Colt-Browning machine gun, commonly nicknamed the "potato digger" due to the behavior of its unique operating mechanism. Invented by John Moses Browning in 1889, the M1895 was an air cooled, closed bolt, belt fed machine gun. It had a gas port on the bottom of the barrel, roughly six inches from the muzzle, which impinged on a piston attached to a long lever. Upon actuation, the lever would swing in an arc down and back, cycling the action in a manner similar to a lever action. The nickname "potato digger" was the result of the gun's behavior when fired from a prone position; if fired from too low a position, the piston's arc would result in it digging into the ground. The M1895 was made in a number of calibers, and saw service through World War I with US and Russian troops.

Here is the discussion, copied from Asam10's talk page:

Gas lever operation

I'm not sure I agree with your logic. First, by the logic you gave, a pump action and a lever action would be the same thing (and in fact, the typical gas operated rifle is just a pump rifle--had Browning been working on pump actions rather than lever actions in the 1880s, he'd have built it that way). In addition, how would you describe Browning's original prototype? It was basically a .44 lever action rifle that used the muzzle blast impinging on a plate to actuate the lever. Is that short stroke or long stroke? There is no cylinder or piston at all in that case, so the definition breaks down. I'm not sure in the M1895 if there is a cylinder/piston or not, it may just be a hole and a plate, so again, you get a breakdown in the short stroke/long stroke definition. Had it been any other firearm, I'd just classify it as an oddity and leave it out, but since it was the first practical gas operated mechanism patented, I think it's important enough to merit a significant description. scot (talk) 21:26, 7 August 2008 (UTC)

These are two unique systems (one with a flapper at the muzzle, the other with a refined flapper operated by a piston perpendicular to the bore axis. Several issues. First, you listed this system at the top though there are only two firearm models I'm aware of, one of which was a prototype. Second, the operation of the bolt is through a series of levers, but the power provided to the bolt is through a gas piston. Though it might seem novel, it's simply a Rube Goldberg way of doing the same thing, extraction, ejection, and feeding. Though core to the argument is how to classify this and where to put it. I'd suggest a discussion on the talk page prior to adding anything back. --'''I am Asamuel''' (talk) 22:30, 7 August 2008 (UTC)

So here are some discussion points:

• What about the prototype .44 rifle Browning made? It was, from his son's description to Hatcher, a modified lever action rifle, using a lever actuated by muzzle blast--this would make it, but the given definition, a "negative stroke" system, as the gas is vented before it actuates the lever. Both that and the M1895 were covered by the same patent.
• What about direct impingement? Take the M-16 and Mini-14 operating systems; in both cases, gas is directed out the port, down a tube, through a fixed piston and into a cylinder in the bolt carrier/operating rod (which serve the same purpose). The only difference is the length of the tube (under and inch vs. about a foot) and the size and shape of the bolt carrier. And yet the M-16 is a direct impingement and the Mini-14 a short stroke design.

And, perhaps most important:

• Is there a source that calls the M1895 a short stroke action? I haven't been able to turn one up.

In addition to the question of adding lever operation as a separate type is the issue of history. To my knowledge, Browning's 1890 patent was the first for a gas operated mechanism--this is why I put it at the top of the list. The development of the M1895 should be mentioned for historical reasons if nothing else--including the Marlin gun variant, which used a linear piston virtually identical to most modern gas operated machine guns. scot (talk) 00:12, 8 August 2008 (UTC)

There is some debate about whether Browning was the first to utilize gas operation (though I'm solidly in the Browning camp). As for where to classify the Browning systems, we would and should explain the systems a bit better. Essentially, gas systems are classified as short stroke, long stroke, and gas trap based on where they utilize gas, either: high pressure, low pressure, or at the muzzle. The first Browning gas operated rifle should rightfully be a gas trap system. The Potato Digger should then fall under the short-stroke section. It is, indeed, as short stroke though it does not use the more modern linear method of transmitting its energy back to the bolt. There are numerous methods for operating the action, though, and none of them are truly linear. They either rotate the bolt (thus 'rotating bolt' in the description) or tilt the bolt through a cam or lever. As a more descriptive definition of operation, the M1895 would be gas operated, lever actuated, tilting bolt (maybe... Not sure as I've never disassembled an M1895). --'''I am Asamuel''' (talk) 00:39, 8 August 2008 (UTC)

I put up a diagram of the M1895 in the article--it's a tilting bolt. The mechanism is pretty complex due to the need to feed rimmed cartridges from a non-disintegrating cloth belt. As for the high, low, and trap classification, I'm not sure if I can think of a truly high pressure system other than the Desert Eagle, which taps right in front of the chamber, and uses a long port drilled into the bottom of the barrel to route the gas up to the cylinder/piston. The Garand would be the definitive low pressure, with the port an inch back from the muzzle, and just about everything else would be in between. Then you've got oddball things like the floating chamber of the Colt Ace--is it blowback, or unlocked gas operation, or is there really a difference? I ran across someone years ago who was considering making an ultralight 10/22 bolt and adding a gas piston that tapped right in front of the chamber, so it would operate (in theory at least) with CB longs. Two holes in the chamber end of the barrel, a set screw to block one off, and a bit of Al bar stock on the bolt, and you've replicated the Colt Ace in a new form; it works the same, but you can't call it a "floating chamber" any more, so is this "gas assisted blowback" a new thing? Maybe the sections are too strong, and imply a sharpness of division that is just not there in reality. Maybe get rid of the sections, define commonly used variants, and note that it's more of a range than set of discrete elements. scot (talk) 01:54, 8 August 2008 (UTC)

We're trying to pigeon-hole these things, of course, however the three classifications are generally distinct from a design point of view, however let me clarify what I mean by High Pressure. High pressure is generally the rear 2/3 of the barrel. From a design standpoint, ports drilled here require some sort of gas cutoff or vent system to operate properly. The M1 Carbine is the best example of a port drilled fairly near the chamber. Been 20 years since I cared enough to examine a Desert Eagle... never had much use for this gimicky gun. But, I digress. The distinguishing feature of a short-stroke operation, therefore, is that it vents, cuts off, or stops the piston after a short travel to prevent abuse of the gun. The M1895 simply vented directly into the atmosphere as does the MINI-14. Yes, the Garand is the perfect example of a long-stroke system. The M1895 is really obscure for the general public and as the operating system is essentially a leverage actuated short-stroke piston, maybe this minutia belongs under firearm actions instead? Rotating bolt, tilting bolt, toggle-locked, roller locked, hmmm. Not really working out in my head right now what to call it. --'''I am Asamuel''' (talk) 05:08, 8 August 2008 (UTC)