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Intro

Percussion cap lock is very familiar to us. Typically it is similar to the flintlock in looks. But actually there was another practical cap lock in history and both have very different mechanical structures but people used it fewer than the common cap lock structure. So today let's talk about this muzzleloader lock.

Another Cap Lock

Ok what is this cap lock. Usually it is called back action lock. And sometimes it also has another name, French action. Because the back action lock was used less in history than the common percussion cap lock, now it is not easy to find the corresponding video/articles, especially the shooting video/articles. If we want to find it out, we will have to change the key words. Like, we can search for the Brunswick rifle. Because according to my study, Brunswick rifle should be one of the rifles that probably half of it used the back action lock but many back action brunswick rifles still have some signs, which is showing out they used the common cap lock at first but we might be not able to know when they were modified into the back action lock rifles.

The most obvious feature of back action lock should be the shape. Although all kinds of the percussion cap lock have the same principle, igniting the gunpowder by striking the priming cap, the hammer of common cap lock is on the middle of plate and the hammer of back action lock is on the front of the plate. And now let’s talk about how it works.

How It Works

Actually it’s very easy to understand. I think when you see this picture, you will know it very clearly. There is a gear, which connects with the hammer and there are 2 teeth to support the 2 positions of hammer, half cock and full cock, which are the same with the common cap lock and the flintlock and the bigger groove connects with the main spring and the spring can give the gear power and the gear can force the hammer turning and striking the priming cap. Although the back action lock in the picture has one spring, based on the pictures of back action locks on the Internet, most back action locks have 2 springs, one spring is the power source of the gear and the hammer. The second spring is smaller and we can call it the sear spring, which can help the sear be fixed and back to the original position.

https://www.muzzleloadingforum.com/threads/back-lock-photos.120848/

https://www.trackofthewolf.com/Categories/PartDetail.aspx/763/1/lock-lr-800

Compared with the common cap lock and when we put the common cap lock and the back action lock together in the same place, we can find that it seems the back action lock is a little bit simpler in mechanical structure. We even can use only one spring but the back action lock was always not the mainstream. Most of the cap lock muskets or rifles always used the common cap lock. But unfortunately, I didn’t find a certain answer as to why there was this situation in history. Maybe with learning more and more muzzleloader historical stories, we can slowly see the evolution route.

In East Asia

Additionally, I also found an interesting phenomenon. There are many East Asian traditional matchlocks that use the back action lock as their upgrading parts. We know that in the 19th century, the East Asian military weapons were extremely quick to be changed into the percussion cap lock muzzleloaders from the traditional matchlock before the bolt action breech loader era. Between the stage of full matchlock time to the stage of fully changing to cap lock muzzleloaders, there was a transition stage. At this stage many mixed situations appeared. Like, the people started to modify the matchlock or a part of people already used the western cap lock guns but another part of people still used the traditional guns, etc.

https://digicol.dpm.org.cn/cultural/detail?id=8854268dc1924076a710a9048b07dc46&source=1&page=1

Therefore, nowadays we can see many cool collections that very obviously were from the transition stage. Because the gun stock, barrel, and other small parts were still the original parts but the traditional match-lock had been removed and the new cap lock had been fixed on the original position. Since the traditional East Asian guns were extremely different from the European guns. So most of the modified guns used the customized cap lock. According to the shape, they are very similar to the back action lock.

https://www.xn--u9j370humdba539qcybpym.jp/part1/archives/362

In fact, the traditional East Asian guns used back action lock, it makes sense as well actually. Most of the modified guns were the East Asian snap matchlock guns. And then the East Asian snap matchlock has many similar features to the back action lock. I think the most important point is the cock position. The original matchlock cock is also in the front of the plate. So this feature might be the factor that the back action lock is more matching the traditional East Asian snap matchlock guns, more strictly speaking, the matchlock stocks. Plus, the back action structure is not very complex so it probably was more fit to customize and install on the original stock.