Push feed and controlled feed (or controlled round feed) are two main types of mechanisms used in firearms to describe how the bolt drives the cartridge into the

chamber Chamber or the chamber may refer to: In government and organizations * Chamber of commerce, an organization of business owners to promote commercial interests *Legislative chamber, in politics * Debate chamber, the space or room that houses delib ...

and extracts the spent casing after firing. * The push feed system does not grip the base of the cartridge before the cartridge has been fully entered into the chamber, and therefore under normal operation requires the cartridge to be fully chambered before it can be extracted. * The controlled feed system grips the base of the cartridge with the extractor claw before the cartridge is stripped from the magazine, and therefore makes it possible to extract the cartridge before it has been fully chambered. The better of the two systems has been debated for over 50 years, and both systems have their strengths and weaknesses. Some prefer the controlled round feed for hunting on dangerous game, while others state that either of the systems can be reliable or unreliable, depending for example on the quality of the rifle and maintenance. There has been a trend that newer rifle models tend to have a push feed mechanism, while almost every modern semi-auto pistol has a controlled round feed. A push feed system is in most cases cheaper to manufacture.

History

The first rifle with a controlled feeding mechanism was the

M1885 Remington–Lee The Remington–Lee is a bolt-action, box magazine repeating rifle designed principally by James Paris Lee. Description It first appeared in 1879, manufactured by the Sharps Rifle Manufacturing Company. Eventually Remington took over producti ...

which first appeared in 1879. Lee applied for a patent, around the same time as Mauser applied for a patent on the same feature, DE51241 and US476290, which was introduced on the

Mauser Model 1893 The Mauser Model 1893 is a bolt-action rifle commonly referred to as the Spanish Mauser, though the model was adopted by other countries in other calibers, most notably the Ottoman Empire. The M1893 was based on the experimental M1892 rifle, whic ...

Discussion

Double feed

The main disadvantage with a push feed system is the possibility for a double feed malfunction if the bolt is not fully closed when chambering a round, followed with pulling the bolt back to strip another round from the magazine, resulting in one chambered and one partially chambered round. A double feed in itself is somewhat uncommon as an independent malfunction, but it often manifests itself as a consequence of other firearm malfunctions. A controlled feed mechanism should in theory not be able to double feed if it is set up correctly. In practice, however, double feed malfunctions sometimes also occur with controlled feed mechanisms.

Safety during case rupture

Push feed mechanisms in theory give the opportunity to design a safer firearm when it comes to a case rupture (for example due to overpressure or excessive headspace) since the bolt head can be designed with a smaller extractor claw which in turn gives the rest of the bolt head a bigger surface area and therefore better support for the cartridge during firing.

Ejector types

Most push feed mechanisms use a spring loaded plunger type of ejector situated at the breech face, and this system ejects the spent casing as soon as the case mouth clears the ejection port. Most controlled feed mechanisms use a fixed mechanical ejector attached to the receiver, which results in the bolt having to be pulled all or almost all the way back to eject the spent casing. This can give a marginally quicker cyclic rate with a push feed action, since the bolt no longer has to be repeated as far or all the way back.

Hand feeding directly into the chamber

Most controlled feed mechanisms should not be closed on a chamber already containing a cartridge (similar to how a push feed mechanism would operate). On short term this can result in difficulties with closing the bolt, and therefore also difficulties with extracting the unfired cartridge from the chamber. On long term, the extractor may be damaged or take significant wear if so is done, since the extractor claw on most controlled feed mechanisms has not been designed to slip over the rim of a chambered round. As a result, controlled feed mechanisms should always be fed with cartridges which first have been filled into the magazine. One notable exception to this principle is the line of rifles based on the

Ruger M77 The Ruger M77 is a bolt-action rifle produced by Sturm, Ruger & Company. It was designed by Jim Sullivan during his three years with Ruger. The rifle features a traditional Mauser-style two-lugged bolt with a claw extractor. Design and feature ...

. This includes the Ruger M77 Mark II and Ruger Hawkeye rifles. While possessing a claw extractor and operating on the controlled feed principle, the M77 rifles have a "Mauser-type" bolt which is also designed to be able to "jump" over a round already in the chamber. This means that it is possible to feed a round directly into the chamber, as is possible with push-feed designs. Push feed mechanisms on the other hand have extractor which are designed to move around the rim of an already chambered round, and cartridges can therefore either be fed via the magazine or hand fed directly into the chamber (sometimes called "single loading").

Example firearms

Using controlled feed

Mauser M98 Mauser, originally Königlich Württembergische Gewehrfabrik ("Royal Württemberg Rifle Factory"), was a German arms manufacturer. Their line of bolt-action rifles and semi-automatic pistols has been produced since the 1870s for the German arm ...

Winchester Model 70 The Winchester Model 70 is a bolt-action sporting rifle. It has an iconic place in American sporting culture and has been held in high regard by shooters since it was introduced in 1936, earning the moniker "The Rifleman's Rifle". The action has s ...

(pre-1964) * Ruger M77 line *

Sako 85 Sako 85 is a bolt-action rifle produced by the Finnish manufacturer Sako since 2006, and the name signifies that Sako celebrated 85 years that year. The model 85 is marketed as one of Sako's premium models for hunting, and is delivered in many ...

* M1911 pistol

Using push feed

* Mosin–Nagant *

Weatherby Mark V The Weatherby Mark V is a centerfire, bolt-action rifle manufactured by Weatherby of Sheridan, Wyoming. The rifle was introduced in 1957 by Weatherby and was designed to safely contain the high pressures associated with the Weatherby line of high ...

Colt AR-15 The Colt AR-15 is a lightweight, magazine-fed, gas-operated semi-automatic rifle. It is a semi-automatic version of the M16 rifle sold for the civilian and law enforcement markets in the United States. Colt's Manufacturing Company currently ...

(post-1964) *

Remington 700 The Remington Model 700 is a series of bolt-action centerfire rifles manufactured by Remington Arms since 1962. It is a development of the Remington 721 and 722 series of rifles, which were introduced in 1948. The M24 and M40 military sniper ...

Sako 75 The Sako 75 is a bolt-action rifle produced by the Finnish manufacturer SAKO, Sako from 1996 until it was replaced by its successor, the Sako 85 in 2006, and finally discontinued in 2007. History The Sako 75 was named after the 75 year anniversa ...

Ruger American Rifle The Ruger American Rifle is a family of budget-level hunting/ sporting bolt-action centerfire rifle made by Sturm, Ruger & Co., which also produces a line of rimfire rifles with similar designs called the Ruger American Rimfire. Design The Ru ...

References

External links

How Does It Work: Push Feed vs Controlled Feed
Forgotten Weapons {{Firearms Firearm components