Monday, September 13, 2010

Actions: Recoil Action: Long Recoil Operation

In the last few posts, we talked about a particular type of recoil action called the short recoil operated action. In this post, we will talk about another type of recoil action, the long recoil operated action.

This action is actually one of the older recoil operated actions in existence, being over 100 years old at least. It is commonly used in naval guns or artillery, but not as mucsh seen with small arms. When it comes to small arms usage, it is mostly used by some well known semi-automatic and automatic shotgun designs. The long recoil action shotgun was originally designed by the famous gun designer, John Browning in 1898 and patented in 1900. This action is very rarely used for pistols and there is only one (Frommer pistol) that used it for a pistol.

In a long recoil operation, the bolt and barrel are allowed to recoil, similar to that of a short recoil operation. At the point when the bullet is fired, the bolt and barrel are locked together. As the weapon fires, the bolt and barrel move back together due to the recoil. They continue to move together backwards until they reach the back of the receiver and recock the hammer. At this point, the bolt is held in the back of the receiver by a catch. The barrel is then pushed forward by a barrel spring and returns completely forward, during which time the spent cartridge case is ejected. When the barrel has reached its fully forward position, the bolt is then released from the back and pushed foward by another spring. As the bolt moves forward, it picks up a new cartridge from the magazine and pushes it into the barrel chamber.

As you can see in the illustration above, the first image shows the bolt and barrel right after the bullet has been fired. Note that the bolt and barrel each have their own individual recoil springs. The second image shows the bolt and the barrel moving backwards due to the recoil until they reach the end of their travel, whereupon the bolt hooks on the catch and is left held there. Meanwhile, the barrel recoil spring uncompresses and pushes the barrel forward, as shown in the third image. When the barrel reaches its forward position, it releases the catch that is holding the bolt back in the third image and the bolt is then pushed forward by the bolt recoil spring.

Compared to the blowback actions we've studied previously, this type of action can handle much heavier loads.

Compared to the short recoil operated action, there are some significant differences.
  1. When the weapon is fired, the bolt and barrel move back together initially, just like in a short recoil operated action. However, in the short recoil operation, the two move back together only a few mm. at most, before the barrel stops while the bolt continues to move backwards. In the long recoil operated action, the separation of the bolt and barrel happen much later. In fact, in a long recoil operation, the bolt and barrel move all the way backwards until they reach the end of their travel in the back of the receiver.
  2. Short recoil actions tend to have only one return spring. Long recoil actions have separate return springs for the barrel and the bolt.
Since the bolt and barrel are much heavier than the bullet and since they move backwards together a long way compared to a short recoil operation, the cycle time of shooting and reloading is much slower compared to a short recoil action or a blowback action. On the other hand, the longer cycle time leads to slower, smoother operation.

The long recoil operated action was used in the John Browning designed Auto-5 shotgun, which was the first semi-automatic shotgun. This shotgun was originally designed in 1898. The Browning Auto-5 model was designed with the intention of making it suitable for mass production and the design was licensed out to various manufacturers, such as FN, Remington, Savage arms, Franchi etc. and remained in production until 1999. This makes this model one of the most successful shotguns in history.

Remington Model 11 shotgun, which uses the Browning designed long recoil action.
Public domain image.

When John Browning had originally designed the Auto-5, he intended to sell the design to the Winchester arms company, since he had already sold several designs to them previously. However, Winchester was not prepared to pay the amount of royalty that Browning demanded, so he went to Remington next. Tragically, the Remington deal fell through, as the president of the Remington company died of a heart attack during the negotiation period. Hence, John Browning went to Europe and licensed the design to Belgium's Fabrique Nationale (FN). Later on, Remington licensed the design again and used it with their Model 8, Model 11 and Sportsman model shotguns. The design was also later licensed to Savage Arms of the US, Franchi and Breda of Italy and Tula State Arsenal (TOZ) of Russia. The French designed Chauchat light machine gun of World War I also used a version of the Browning long recoil action mechanism. While the Chauchat was mostly a failure, the shotguns remained in use for a very long time indeed.


  1. The Remington model 8 and 81 were also long-recoil designs and also designed by John Browning. They were popular for a time. Having fired one, I've come to strongly suspect that long-recoil operation increases felt recoil. I'm not sure if this is because of the large center of gravity shift of the parts moving so far in the receiver or because of elastic collision between the receiver and the moving parts. I do know for sure that I and one other experience shooter did not wish to fire more than five rounds apiece through the 81 as we found it to be extremely unpleasant. Both of us had fired .416 Rigby elephant guns before with no undue discomfort!

    Interestingly though, the Steyr AMR was slated to use long-recoil operation on the grounds that recoil could be more effectively buffered by the long parts travel. Go figure.

    1. I have shot several model 8s and 81s. I have had exactly the opposite reaction. The long recoil operation felt significantly lighter to me.

  2. The Madsen Light Machine Gun (LMG) was also long recoil-operated, although using a different system with a swinging breechblock that would not separate itself from the barrel. Instead, the breechblock would swing upwards during the recoil, enabling the extraction and ejection of the cartridge case. During the returning, the breechblock would swing downwards, enabling the feeding of a new cartridge. Then, at the end o the cycle, the breechblock would re-align itself with the bore axis, ensuring the locking.
    Some authors call Madsen’s system as a “short-recoil” or “mixed recoil-operated”. I disagree, as I’ve been taught that when the barrel recoils longer than the cartridge length, it is a “long recoil”. That is the case of the Madsen LMG.