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A collaborative effort of the Marlin Owners moderator staff
Videos by Travis "186 Tmanbuckhunter"
Text by Ryan "miatakix", Ken "Leverdude", and Travis "186 Tmanbuckhunter"
Photos by Ken "Leverdude"
Creative directing by VTDW
Special thanks to Ridgerunner665, swany, Eli Chaps, and Barenjager
Understanding and safely using the half cock notch on the Marlin lever-action


Video
The following video demonstrates how to properly engage the hammer's half-cock notch on a Marlin lever-action rifle:

Video 1
halfcocksafetyvid.mp4 video by Dp908 - Photobucket

This second video demonstrates how it is possible to reliably reach the "false half-cock" position on any Marlin lever-action rifle when the proper procedure as shown in the video above and the factory user manual is not followed, and the finger is kept on the trigger while attempting to put the hammer into half-cock. This has the potential to create a dangerous and deadly situation as the weapon likely WILL fire if the trigger is pressed, and is only shown here for demonstrative purposes. Always observe the four rules of firearms safety and understand how the factory user manual describes how to operate your firearm:

Video 2
falsehalfcocksafetyvid2.mp4 video by Dp908 - Photobucket

Intro
We at Marlin Owners would like to clearly illustrate and explain how the lever action Marlin's half-cock mechanism is designed to work and be manipulated by the user for maximum reliability. It is our belief that a thorough understanding of the design and intended use of this feature will allow the user to maximize the safe operation of their Marlin rifle and make an informed decision on how YOU are most comfortable operating your rifle. We hope that the videos above and the article that follows will give you the resources to do so. However, we take no responsibility for your safety, that is your concern and responsibility. Always observe proper firearms safety and read and understand your rifle's user manual.

The feature that will be addressed here is the half-cock notch on the hammer. The half-cock notch has traditionally been used as the primary mechanical safety device when carrying a lever action rifle with a cartridge in the chamber. Contemporarily manufactured Marlin lever action rifles have integrated a cross-bolt safety into the receiver to add an additional mechanical safety mechanism . This adds a second mechanical safety that when engaged physically blocks the hammer from being able to strike the firing pin, but these may not always be convenient to some owners, so completely reliable operation of the half-cock notch remains critical to the acceptability of any Marlin lever action rifle for safe use. A previous article by Travis "186 Tmanbuckhunter" has suggested some practical tests to ensure this, which can be found stickied in the Basic Triggers section of the Gunsmithing subforum here:

Basic trigger safety tests: Bump test and push off test

What half-cock engagement looks like
The operation of the half-cock notch can be understood by observing the hammer's geometry and rotational position relative to the sear, which is tilted into and out of engagement with the hammer by manipulation via the trigger. This properly engaged relationship is depicted in the following pictures:

Picture 1. The firing mechanisms installed in the trigger plate with the sear engaged in the half-cock notch.


Picture 2. Again showing just the hammer with the sear engaging the half-cock notch.


How half-cock engagement works
In the following cut-away diagram of the fully assembled Marlin lever action receiver one can see how we can get to this half-cock state as the hammer is pulled back from the fully decocked, hammer-lowered position when the bolt is locked forward:

Diagram 1. Cut-away depiction of the fully assembled Marlin action


The sear's position relative to the half-cock notch as we start allows no engagement between the two, the sear is forward of and free from the half-cock notch. At this point if the user pulls the trigger, the trigger causes the sear to rotate forwards (clockwise in the diagram) away from the hammer. This motion is counteracted by the sear spring, which tends to pull the sear towards the hammer to engage with and bear upon it (in the rearward, counterclockwise direction, in the diagram). Notice that the hammer rotates on the large pin (white in the diagram), and on the bottom of the hammer exist two notches that interface with the sear, a deep notch (the half-cock notch that we saw engaged in pictures 1 & 2) and a shallower notch (the full cock notch, which resides directly above the sear axis pin in the diagram).

As the firing mechanism in the rifle in Diagram 1 sits, the hammer is fully forward/decocked, and the sear is forward of the half-cock notch. At this state of readiness, any user initiated pull on the trigger would cause the sear to rotate forward, but nothing of consequence happens as a result. You can verify this by grabbing your (verified as unloaded) lever action rifle with the hammer down and pulling the trigger. The hammer will not move. The force of the hammer spring will keep the hammer firmly pressed upon the firing pin. Note for later that this is not a particularly safe position for the hammer to be in with a live round in the chamber, since if the rifle is dropped or bumped in any way such that a large enough force is exerted upon the hammer spur, the rifle could inadvertently fire without manipulation of the trigger.

Now, with the hammer starting in the fully lowered, decocked position, if one leaves their finger off of the trigger and pulls the hammer partially but not all the way rearward from this position then eases the hammer forward, the sear will engage the half-cock notch as shown in Pictures 1 & 2 due to the force exerted by the sear spring, which allows the sear to slide into and fully engage the deep half-cock notch. At this state of readiness if the trigger is pulled nothing happens as the forward edge of the deep half-cock notch retains the sear in a static position due to the mechanical retention of the sear by outer protrusion of this notch in the hammer, and their orientation relative to the direction of rotation of the hammer. So the sear tries to move away from the hammer (clockwise in the red diagram) with the force applied to the trigger, but the front end of the half-cock notch blocks the movement of the sear (and thus the release of the hammer and striking of the firing pin) by design.

Also notice that whatever force the sear exerts on the hammer in this position is mostly radial. The engagement surfaces of the sear and half-cock notch here are mostly perpendicular to the designed direction of travel for the sear, which in turn is situated such that very little force is exerted on the hammer that may cause the hammer to rotate in one direction or another. In other words this is a similar concept that explains why you cannot push a car by pushing straight down on one of its wheels. You just aren't pushing things in the right direction to initiate movement/rotation.

Therefore the sear is mechanically linked to the hammer at this state of operation and thus the rifle is safe, unless either the hammer breaks from a very large external force such that the forward edge of the half-cock notch is sheared off, or if the hammer is manipulated back towards the full-cock notch by the user so that the sear may slip out of the deep half-cock notch.

Moving back to fully cocked
As the hammer is thumbed back to the full-cock notch and engages it and comes to a rest, sufficient movement of the trigger is now free to move the sear (clockwise in Diagram 1) away from the hammer such that the hammer released from the restraint of the sear and is able to fall under the force exerted on it by the compressed hammer spring acting on the hammer strut. This relationship can be seen in the following pictures:

Picture 3. Marlin hammer at full cock


If the trigger is pulled and held back from here, without other intervention the hammer will fall all the way forward and strike the firing pin with full force, which will ignite the primer of any live cartridge that may be in the chamber.

Engaging the half-cock safety the way the Marlin manual recommends
If the user arrests this fall of the hammer from the fully-cocked position by restraining the hammer motion with their thumb placed on the hammer spur, the hammer may be lowered back to the half-cock notch position. You may want to ride your thumb farther forward on the hammer spur to obtain a nice firm purchase of the hammer spur to minimize any chance of slipping, and if you go far enough forward you may even be able to allow your thumb to catch or block the hammer from falling if you do slip. Better a slightly pinched thumb than an inadvertent discharge.

The advantage to engaging the half-cock notch this way, by lowering from full-cock, is that one never need allow the hammer to rest upon the firing pin. However, accomplishing this manipulation safely and reliably requires the user to completely remove their finger from the trigger immediately following release of the sear from full-cock notch and enough forward excursion of the hammer to just pass the full-cock notch. One can know that this has happened when the hammer begins exerting forward pressure on the thumb, as at this point the sear is no longer restraining the hammer. At this point remove your finger from the trigger and trigger guard area. If this is done the sear will be free to reengage the half-cock notch using the force from the sear generated by the sear spring. If the finger is not removed from the trigger and even a small amount of pressure remains on the trigger, the user will overcome and defeat the purpose of the sear spring and the sear will remain rotated away from the hammer such that the hammer either bypasses the half-cock notch altogether (which is part of the design, so that the rifle can be fired) or only partially or precariously seats on the outer apex of the half-cock notch without the sear seating fully into the notch, as can be seen in Pictures 4 & 5. This could result in a dropped hammer upon further pulling of the trigger. The rifle might fully engage the half-cock notch, but it cannot safely be assumed that this will happen with the finger remaining on the trigger. The possible precarious state of readiness mentioned is known as a "false half-cock," and is demonstrated in the following pictures.

Picture 4. False half-cock. Marlin hammer resting on top of half-cock notch as can happen if the user doesn't fully release the trigger BEFORE lowering the hammer.


Picture 5. False half-cock. Marlin hammer resting on top of half-cock notch as can happen if the user dont get his finger off the trigger before lowering the hammer.


Note that in such a false half-cock position, there is nothing to restrain the movement of the sear away from the hammer if the trigger is pulled, and a resulting release of the hammer energy onto the firing pin, RESULTING IN A POSSIBLE DISCHARGE. Also note that due to the uncertainty of how the sear and hammer may be engaged here, THE TRIGGER PULL (IN POUNDS) REQUIRED TO RELEASE THE HAMMER MAY BE LESS THAN THAT REQUIRED TO RELEASE THE HAMMER FROM THE FULLY-COCKED POSITION.

Also note that the manufacturing quality and design of the half-cock notch and sear engagement surface plays a role in how likely this state of false half-cock is likely to occur with improper lowering of the hammer to half-cock (i.e. failing to remove one's finger from the trigger after releasing the hammer from the fully cocked position). The following Marlin hammer shows a flat surface on the half-cock notch that makes this more likely to occur:

Picture 6. Marlin hammer with flat surface on tip of 1/2 cock notch that will make the hanging up of the hammer on the sear more likely.


BUT EVEN THIS SHOULD NOT BE A PROBLEM SO LONG AS THE PROPER PROCEDURE OF KEEPING THE FINGER OFF THE TRIGGER AS THE HAMMER IS LOWERED IS FOLLOWED.

Finally, we would like to demonstrate that this design with its accompanying possibility to be put in a "false half-cock" state with improper use is not limited to the Marlin, but in fact is a possibility with ANY firearm that uses a conventional 1/2 cock system from 18th century flintlocks to Marlins, Rossis, and Henrys of current manufacture and Winchesters or Brownings of recent manufacture.

Picture 7. Winchester hammer with half-cock notch.


We leave you with the Marlin 1894 User Manual statement of how to properly engage the half-cock feature:

3.To Move the Hammer
to the Half cock Position

First put the hammer block safety on
SAFE. The hammer may be moved from
Full cock to the Half Cock position by firmly
holding the hammer in the Full Cock
position with your thumb. Keep your thumb
on the hammer as you pull the trigger. As
soon as you feel the hammer exerting forward
pressure against your thumb, remove
your finger from the trigger and ease the hammer slowly forward to the Half Cock
position (See E & F). The hammer is now
in the traditional Half Cock “Safe” position.
 
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