Talk:Blowback (firearms)/Archives/2013

Created new article, moved some content
I've moved the section of this article discussing blowback as the vacuum evacuation of a firearm's barrel to a new article at blowback (forensics)

Paintball and airsoft blowback
Maybe I should've discussed it in the talk page before editing, but I do think that blowback for paintball and airsoft guns does warrent at least a cursory mention here. It's exactly the same operation; pressurized gases primarily used for the propulsion of a projectile are also partially used to cycle the action. The only difference is that in firearms, the gases come from a chemical reaction, where in paintball/airsoft guns they come from a reservoir, be it the gas chamber in a pistol mag, or a bulk CO2 tank. --UNHchabo 20:54, 31 March 2006 (UTC)
 * I don't doubt you at all on how they operate. However, I don't think they belong in an article about firearms.  They are, by definition, not firearms and therefore while the principle might appear similar, it is a totally different useage. It would be proper to list it under the disambiguation page instead if you deem it important enough.  --Asams10 21:15, 31 March 2006 (UTC)

Proposed merge from various blowback stub articles
AGREE I think if we put all the little stub blowback articles into this we'd have one very nice article. Toggle-delayed blowback Roller-delayed blowback Lever-delayed blowback Gas-delayed blowback Blowback (forensics) Chamber-ring delayed blowback Arthurrh 18:52, 1 September 2007 (UTC) Ok, I agree with the logic. I've removed the merge request. Arthurrh 17:13, 4 September 2007 (UTC)
 * Agree, except the forensics one. Leibniz 20:59, 1 September 2007 (UTC)
 * Agree, And I merged most of them, but I agree with Leibniz and will nog merge the forensics one with this one, as it is not abot a blowback type, but about a vacuum effect. If consensus about this is reached, we can remove the merge tag. --Boris Barowski 14:21, 4 September 2007 (UTC)


 * Based on the concensus expressed, Boris has merged the articles and fixed some redirects, I've gone through and cleaned up the resulting redundancy as well as tried to order and format the article for readability. I also added some references and a section on piston primer operation that is more a form of blowback than it is gas operation.--Asams10 16:54, 5 September 2007 (UTC)

schematics and images
This article could use some schematics, drawings or pictures to illustrate the different systems. --Boris Barowski 18:45, 4 September 2007 (UTC)
 * I've got the Pedersen Patent that I think would produce a fine drawing with a little coloring for hesitation blowback. I'd like to refine the other Pedersen patent drawing for toggle-delay for clarity too, take out the lines and numbers and color it in some. If there's a good 'lever-delay' one out there as well as piston primer one, that'd help out alot.--Asams10 16:57, 5 September 2007 (UTC)
 * I added the reqphoto template - ideal would be an animated GIF showing how it works. Tempshill 06:03, 15 November 2007 (UTC)

Asams10 - CETME Ameli - roller-delayed blowback
Regarding the CETME Ameli light machinegun - I added this to the "roller delayed" subsection of "delayed blowback", but you reverted this, stating "rv: incorrect, roller locking and roller-delayed blowback are not the same thing."

I agree with you that roller-locked short recoil systems with moving barrels (for example, the MG42) are "not the same thing" as roller-delayed blowback firearms with fixed barrels (e.g. CETME Models A, B and C, HK G3).

However, according to the Ameli's manufacturer, General Dynamics Santa Bárbara Sistemas (sorry, I can't link directly, as that site uses frames):


 * "The machine gun has a CETME semi rigid bolt system using rollers permiting (sic) the use of any ammunition of the appropriate caliber." GD/SBS site, click on Products and Projects / Weapons Systems / Light Weapons / Ameli - Light Machine Gun

I interpret this as the Ameli using the same roller-delayed blowback system as the CETME rifles.

The Ameli may externally resemble an MG42 that shrunk in the wash, but it has a completely different operating system.

I respectfully request that you restore my edit.

GMan552 (talk) 05:41, 3 May 2008 (UTC)


 * Thank you for your thorough response. I stand corrected on the technical issue, however I have another issue that is more substantial.  While true, there is no reason to have this example in the article as it's highly obscure.  That's a subjective issue, however since I didn't know about it, it's probably not common knowledge.  If you are using it as an illustrative example, you should use examples that are common, well known, etc. This weapon was made in limited numbers and issued only to the Spanish Army according to the Wikipedia Article. However, I'm not sure there is a better illustrative example of a machinegun available. Can we give it a week for other comments? --&#39;&#39;&#39;I am Asamuel&#39;&#39;&#39; (talk) 17:08, 3 May 2008 (UTC)

Fair enough - the Ameli isn't that well-known, although I still wish I could own one (and afford to feed it.)

GMan552 (talk) 17:17, 3 May 2008 (UTC)

Pure Blowback?
I take exception to the term, "Pure Blowback." I do believe it can be listed, however the proper term would be "Simple Blowback". The reason for this is that "Blowback" isn't pure and never can be. The mass of the bolt delaying the ejection of the cartridge is only one of many functions that hold the bolt closed. There is spring tension, friction, and also the fact that the firearm itself is moving rearward due to the friction of the cartridge on the sidewalls of the chamber, spring pressure, and friction. All of these serve some purpose in slowing the opening of the gun and, "Pure" is a misnomer. Common, yes, but still a misnomer. Simple is less absolute and properly describes this type of blowback in relation to other systems that should be interpreted as "complex" as it follows. --Nukes4Tots (talk) 02:33, 13 June 2009 (UTC)


 * Agreed, I have always encountered either "straight" or simple blowback in technical literature. I'm still processing a lot of information and the edits are somewhat raw so give me a day or two to format everything properly. Koalorka (talk) 02:53, 13 June 2009 (UTC)


 * I'll let you continue, then. Chinn is outstanding to read. --Nukes4Tots (talk) 05:38, 13 June 2009 (UTC)


 * His works are some of the most comprehensive ever published on the subject, short of a mechanical engineering text book. Good stuff, highly recommend for anyone researching automatic weapons and the physics involved. Koalorka (talk) 15:39, 13 June 2009 (UTC)

Advanced Primer Ignition Blowback
The explanation of API blowback as ignition happening "before the bolt strikes the chamber face" is misleading because it applies only to submachineguns, or more generally to automatic weapons fairly low-powered ammunition. (See Anthony G. Williams, Rapid Fire, page 65 ff). Because in this variant the case is not fully supported at ignition time, such a design cannot be used in more APIB powerful weapons -- such as the original 20-mm Becker cannon and its Oerlikon derivatives. It is true that submachineguns are now the most common application of APIB, but the historical importance of the large calibre weapons is far too great to ignore them.

See also the description of the the API blowback mechanism in Chinn's reference. The diagrams and detailed technical explanation in Chinn's Vol IV, which include time and position charts for the bolt, make it very clear that in the original APIB design, the face of the bolt followed the case into an elongated chamber. This was the operating principle by the original 20-mm Becker and Oerlikon guns, and their various derivatives and adaptations; for this reason they all used cases with rebated rims.User:Mutatis Mutandis —Preceding undated comment added 16:40, 4 July 2009 (UTC).

Primers are pretty soft. It would appear that with a fixed firing pin, the primer initiation begins when the cartridge is stripped from the magazine. In addition, a chamber "a few thousandths of an inch shorter" would require the bolt to deform the cartridge case in the chamber making extraction more difficult and unreliable. The nature of the deformation would be totally dependent upon individual case characteristics. Are there any references for this part of the design? -JD —Preceding unsigned comment added by 68.20.5.232 (talk) 14:32, 7 July 2010 (UTC)
 * No, and I've deleted it. Someone not using his real name (talk) 02:24, 7 July 2013 (UTC)
 * I've now added a concrete example (the L2A3) from a source that was less vague that the typical gun magazine/website is on this topic. Someone not using his real name (talk) 00:17, 8 July 2013 (UTC)

Requested move

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

The result of the move request was: page moved. Vegaswikian (talk) 05:19, 4 July 2010 (UTC)

Blowback (arms) → Blowback (firearms) — Practically all other firearms disambiguation-type names are (firearms), not (arms). See Magazine (firearms), Cartridge (firearms), Trigger (firearms), Safety (firearms), Chamber (firearms), Receiver (firearms), Cylinder (firearms), Muzzle (firearms), Rim (firearms). Faceless Enemy (talk) 06:07, 27 June 2010 (UTC)
 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

How are Blowback and Recoil different?
--24.6.228.145 (talk) 01:11, 16 February 2011 (UTC)
 * Recoil has locking and unlocking; Blowback does not. Recoil also involves movement of the chamber.  Faceless Enemy (talk) 04:32, 18 February 2011 (UTC)

Pederson and lever-delayed blowback
Cartridges and Firearm Identification By Robert E. Walker p. 25: "Unsuccessful attempts at blowback include the screw delayed and the Pederson hesitation lock, both of which are unlikely to be encountered or appear again." So it seems there's fair bit of a stretch to say that Pederson invented the (workable) lever-delayed later used by Kiraly. I'm requesting a secondary source be used to make that claim, not Pederson's patent, per WP:PRIMARY and WP:OR. Someone not using his real name (talk) 08:43, 3 July 2013 (UTC)

A search in Google Books for Pedersen & Kiraly & blowback doesn't return anything useful. It doesn't look like any historian connected the dots as they are in this article (on this obscure topic). Someone not using his real name (talk) 08:53, 3 July 2013 (UTC)


 * Try Hatcher's Notebook, Book of the Garand, or Chinn. Hatcher actually enumerates these differences quite well. Are you saying that since not enough secondary sources are listed then the information should be deleted? Is there reason to doubt it? Do you have a counter opinion you can back up with secondary sources? A simple glance at the Remington 51 article will give you more references. --Winged Brick (talk) 00:06, 19 September 2013 (UTC)

Postnikov's APT
I'm not sure that qualifies as API. Here's the source-text used to support that claim, which turned out to be a 100% copy of the sole paragraph about this gun from the book История русского автомата (History of the Russian assault rifle) by С. Б. Монетчиков (p. 190): "Одним из наиболее экзотичных и конструктивно сложных являлся автомат Постникова АПТ (практически сразу снятый с полигонных испытаний), в котором автоматика работала по принципу отвода пороховых газов из канала ствола через затравочные отверстия капсюля патрона. Однако в отличие от исследований В.Г. Федорова и А.А. Благонравова, утверждавших, что для этого нужен специальный патрон с утолщенным дном. И.К. Постникову удалось реализовать подобную схему на штатном 5,45-мм патроне. При выстреле давление пороховых газов через капсюль воздействовало на ударник, двигавшийся назад, тем самым отпирая затвор."

The first half of the paragraph says that the APT would have required special cartridges to bleed gases from the bore. It's not entirely clear from that text what Postnikov's workaround for this was. It seems to me that he allowed the primer (капсюль) to be kicked back (perhaps deformed?) instead to allow gasses to escape. Maybe another translation is possible... What we do know from another source in Project Abakan is that APT was the least reliable design, and the first to be withdrawn (Ружьё. Оружие и амуниция, 1998/1, p. 7); so perhaps not really a good example to give here, besides being an incredibly obscure gun, even in Russian literature. Someone not using his real name (talk) 22:13, 6 July 2013 (UTC)

In the older, 1999/2000 book Отечественные автоматы: (Записки испытателя-оружейника) / А. А. Малимон; М-во обороны Рос. Федерации only this much is said about APT: "Особенностью автомата ижевского конструктора И.А. Постникова являлся опробованный в свое время еще отечественным оружейником Токаревым и не прижившийся в мировой практике принцип работы автоматики, основанный на отводе пороховых газов из ствола через затравочные отверстия в гильзе при демонтаже капсюля."

That reads more like APT was one-of-a-kind design rather than using an established paradigm. Someone not using his real name (talk) 23:35, 6 July 2013 (UTC)

TZ-45
The only source I was able to find making the claim that TZ-45 used API is world.guns.ru: "The TZ-45 submachine gun is a simple blowback operated weapon which fires from open bolt. It uses advanced primer ignition principle, and can fire in single shots of full automatic, thanks to combined safety / fire mode selector, located on the right side of the trigger unit, in front of the trigger guard." It doesn't go into any details as to the supposed API operation of this gun. I don't know how reliable that site is for non-Russian stuff. Someone not using his real name (talk) 01:55, 7 July 2013 (UTC)

A more detailed article on forgottenweapons.com, which includes pictures of the mechanism, says nothing of API. Someone not using his real name (talk) 02:15, 7 July 2013 (UTC)

Case setback and primer-actuated
The Russian magazine cited doesn't actually describe these as blowback but as a variant of gas-operation. The case only sets back about half a milliliter in these guns, and the block stays mostly locked as a result. Adding the material to the gas-operated reloading was simply following the source. It did occur to me that Barishev's system has more in common with blowback because of the large movable part, but even in that case, the tilting piece keeps the breech mostly locked during before the large "semi-bolt" (green in the diagram) moves sufficiently far back. Are there any sources (in English or otherwise) describing these as blowback? Someone not using his real name (talk) 07:12, 23 August 2013 (UTC)

The same observation applies to Garand's 1921 primer actuated system. Hatcher's notebook doesn't categorize this as blowback. Someone not using his real name (talk) 07:39, 23 August 2013 (UTC)


 * That is why they are categorized under 'other' blowback systems. Where the setback of the case or a portion of the case (which involves the same power source of pure blowback) is used in whole or in part to actuate the reloading. In the case of Primer Actuation, the ENTIRE cycle is operated by primer setback.  More modern versions are 'piston-primer' and the primer is specifically designed to act as a piston. However, in both cases, the primer is blown back.  In the Williams design, the case is setback by blowback power in a floating chamber, however the face of the chamber is augments the blowback power.  This can be classified as both a blowback and a piston operated system as gas is impinging on the face of the floating chamber.  Williams' system would properly be placed under BOTH gas actuated and blowback actuated.  The Russian system, it appears (reading translation) might operate with a traditional gas piston?  I'm sorry, I don't read Russian so it was difficult to decipher.  I do enjoy Google telling me about a "Rebound Chicken" though. If the piston system provides the power to operate the action and case setback unlocks it, then the only thing unique about it is the blowback portion of the cycle, hence its placement here is proper. Hatcher placed primer-actuation immediately before Williams floating-chamber rifle.  He doesn't categorize it as either a gas or as a blowback operated, but places it where this article places it, alongside 'other' designs.  --Winged Brick (talk) 14:26, 23 August 2013 (UTC)