How Open Bolt Actions Work In Firearms

hello and welcome this is mouse gunner and in this video I'm going to cover open bolt actions and firearms this demonstration will build upon concepts I have already discussed in some of my previous videos and dealt with in greater detail on set videos the open bolt action is quite a bit different than the closeable action seen in the examples in all of my previous videos but as I said earlier some functionality remains the same or is very similar to functions found in closed bolt systems the first example I'm going to cover is the Sten mark 2 which is as far as firearm designs go about as simple as things get outside of homemade slamfire guns the straight blowback open bolt system more or less just automates the firing process found within said slamfire guns you have to forgive the program I use to make these demonstration videos as its presentation can be sloppy at times a particular issue we will have in this video is the fact that all the examples we will look at have the capability of being fired fully automatic when being fired automatically the animations will only start with the trigger pulled so that the animations can cycle one after another seamlessly unfortunately this makes it difficult to show the function of the trigger group and also leads to some inconsistencies with the timing of certain parts with that being said let's go ahead and start off by identifying the major parts we're concerned with the first part is the bolt we have the seer which is in direct contact with the bolt very similar to the way that the seer is in contact with the striker on a striker fired action and we have the trigger which is attached to a trigger bar which is going to act upon the sear the main big difference between an open bolt system and the more commonly found closed bolt system is the fact that the bolt is held to the rear before the pull of the trigger rather than being all the way forward with the face of the bolt up against the chamber and when the trigger is pulled the bolt will be driven forward by the releasing tension of the recoil spring so as we pull the trigger the trigger will pivot which is going to act upon the trigger bar which is going to push outwards towards the front of the firearm and as it gets pushed along it is going to through this contact point here with the sear going to push upon the sear and as the sear gets pushed it will start to pivot down and away from its contact with the bolt here and once that contact has been broken it will be driven forward just like the striker on a striker fired action and it will act very similarly to the way the striker and a striker fired action works so the bolt itself does not have a firing pin within it it actually has a fixed firing pin on the very surface of the bolt face so this little protrusion here is the firing pin and we can see a little bit more clearly and how it is extended out but it will not act upon the primer within the base of the cartridge until it brings it into the chamber so we can see that happening as the bolt drives forward it's going to strip the next round and then feed it into the chamber and once the cartridge is fully seated into the chamber the full momentum of the bolt will act like a hammer on the anvil of the chamber and all of that momentum will be focused into that protrusion the fixed firing pin onto the primer and the base of the cartridge case and as the bolt travels to the rear recoiling under the energy of the expanding gasses pushing the bullet down the barrel the cartridge case will be extracted and ejected just like it would be an a closed bolt system and as we are operating the Stenmark - in semi-automatic mode the Stenmark - does have a select fire feature which we currently have in the single-shot mode it will travel past the seer which comes up ready to catch it so when it is done recoiling and drives forward a bit it will then be caught by the seer and ready for us to pull the trigger again the remainder of our focus in this example is going to be on the trigger group itself and how it functions in single-shot mode or semi-automatic mode and how it works and fully automatic mode and what the difference is so currently we're in the semi-automatic mode and when we pull the trigger as we've seen before the trigger bar is going to act upon the sear until the sear pivots away from its contact point with the bolt but as the bolt is driven forward this part of the trigger bar is going to contact the protruding part of the bolt that the sear is previously holding on to and when it does that it's going to pop the trigger bar down and as the sear returns due to its return spring it will fit so that the trigger bar is underneath this shelf and no longer is this not cheer able to engage the seer so as long as we have the trigger held in and the single-shot or semi-automatic mode the seer will not be tripped again so as the bolt comes back the seer will come up ready to catch it and it's not until we let the trigger out the trigger resets that we can pull the trigger again and fire once again so let's take a look at how the selector switch modifies that system so here's the selector switch and when we activate it it's going to push the trigger bar off to one side and it's when the bolt is dropped by the sear that we have our main big difference so I've taken a alternative look from the bottom of the firearm and as the bullet comes forward the surface that the sear normally holds on to that would normally contact their trigger trigger bar instead goes right past the trigger bar because the trigger bar is being pushed off to one side it no longer contacts that part of the bolt and as a result it is not driven downward and the sear is not allowed to return so as long as the trigger is held in this year will be held down and as the bolt is driven to the rear and then comes forward again it is not going to be caught by the sear and instead would just be driven forward again and continue to do so as long as we held the trigger in now one thing that is important to note with a open bolt fully automatic firearm is that sometimes even when you let go of the trigger depending on the timing the bolt will still drop forward and fire one more time so you always have to be prepared for that so if we continue to watch the cycling here as we've let go of the trigger the bull was still driving forward and fired off one more round so if we had let go of the trigger at the very moment the the bolt had just passed this year it would have still gone forward and fired off another round and we have to be prepared for that with an open bolt fully automatic firearm to occur and with the Stenmark too I can very easily demonstrate the reason why you don't see any new production open-bolt firearms in the United States and that's because the US government regulates the sale of fully automatic firearms now that doesn't mean that fully automatic firearms are illegal it just means that the US government regulates them through the ATF now if we were to activate our selector switch and bring this back into the semi-automatic mode and let's say we're pretending that we were to remove the selector switch and instead replace it with a pin that would permanently hold the trigger bar in this position and we were selling this firearm as a semi-automatic only Stenmark - for the US market well it really isn't all that hard to take this design and modify it for a fully automatic firearm all you'd have to do is cut down this part of the trigger bar so it no longer would make contact with this part of the bowl if it doesn't make that contact the trigger bar isn't driven downward and thus deactivating its contact with the sear so in that instance if we held in the trigger it would continue to hold the sear down and as long as we held the trigger in the firearm would continue to fire and fully automatic mode this is a very easy modification to do now in the past this is something that you used to be able to do legally as long as you documented the modified firearm as a fully automatic firearm once the modifications were made it was perfectly legal to own and operate one of these firearms but the ATF was really concerned about people making these modifications illegally and not registering them after the modifications were done and this is the reason why open bolt firearms are more or less banned in the United States at least new production ones the next example we're going to look at is the ez and we're looking at it not because it differs really an overall functionality with that of the Sten but mostly because I know a lot of people are going to be curious how it works due to its notoriety and would be disappointed if I didn't talk about it view Z is also a straight blowback open bolt action so it works more or less the same as a Sten gun and where it differs it mostly differs in how functions occur rather than having different functions with that being said let's go ahead and highlight the main so we have the bolt here and if we look inside here we can see the fixed firing pin on the face of the bolt and it is the shape of the bolt that is the main innovation of the Uzi it's a pretty unique idea for the time rather than having the bolt be entirely behind wherever you have the magazine instead the bolt actually extends around that point which allows you to have a much more compact design you don't have to have all of that weight behind means that the firearm doesn't have to be as long and that is really honestly a ingenious way of working around some of the limitations of a straight blowback operated system the next part we're going to look at is the seer which we can see actually has two engagement points with the bolt here and here and then we have the trigger right here which is going to act upon the sear now we're going to start off shooting this in semi-automatic mode and as we pull the trigger the trigger through this part in the middle is going to pull down on the Sears which are going to break their contact from the bolt and just like with the Sten gun the bolt is going to come forward rip around from the magazine and then feed it into the chamber and we can see that mean the chamber a little distance the bolt had to travel to get there it recoils back extracts and ejects the cartridge case comes back forward and because we fired this in semi-automatic mode the seers are ready to catch it so let's take a look at the trigger group yet again and focus our attention at that as this is going to be one of the big differences between the stan and the is II just this slight difference in mechanism this time around as we pull the trigger we're going to watch what happens with this piece here that the trigger is attached to and as a trigger pivots this piece is going to be pulled downwards and as it's pulled downwards it's also going to pull the Sears downwards as we've seen before the thing we have to watch out for is what happens after that so after a while with the trigger continuing to be pulled this block here is going to break its contact with the Sears we can see here that this is how this block contacts the sear and once this pivots down enough we can see it's going to eventually break that contact and when it does the Sears are going to come up and in this position even if we were to let out the trigger this block cannot come back in because it will just contact these points and stop at that point and when the bolt comes back the seer is going to come back up waiting to catch the bolt and hold it in place until we the trigger reset allow the block to fall back in place and we are ready to fire again now let's see what happens when we activate the selector that allows us to switch it into the fully automatic mode so before with the selector here and the semi-automatic mode there was this bar that came across the trigger this block here any case to stop its movement but now with this bar out of the way when we pull the trigger what's going to happen is this block is never going to break its contact with the Sears so let's go ahead and pull the trigger and you can see as the action cycles and we'll go ahead and try and pause it at some point there we go this block is not breaking its contact with the Sears because we've changed how it pivots before when we had the selector switch activated let's go ahead and let this action cycle one more time with the selector switch active when we fire this time we see that this block cannot pivot fully and because it can't pivot down and instead is going to pivot backward and as it pivots backward it's going to break that contact with the Sears so just by that little bit of change we change that dynamic and again with the Sten gun as we discuss being able to modify a semi-automatic design if instead of having a selector switch we just had a bar that came across here that would change the block so that it would always act like this all we have to do is remove that bar and with it out of the way it would then function as the fully automatic mode would function so let's go ahead and do that again so with the bar out of the way now that block can pivot downwards and no longer has to pivot backwards and as a result we can modify a summary of at a semi-automatic only Suzy very easily into a fully automatic one the next example I'm going to cover is the mg 3 which is a variant of the mg 42 I suspect that this version is in the program I use because the animations could not keep up with the original mg 42s rather high I fire rate of about 1,200 rounds per minute whereas the post-war mg3 depending on its setup could have a fire rate as low as 900 rounds per minute which is still pretty fast but definitely slower than the original mg42 is an example of a short recoil operated open bolt-action it is a common misconception that open bolt guns have to be straight blowback operated but this is not true an open bolt gun can utilize any operating system that a closed bolt does and although straight blowback open bolt actions are seen commonly and submachine guns like the stan and Uzi we looked at earlier machine guns like the mg42 are more likely to use a lock reach design or delayed blowback action in order to contend with the higher pressures produced by rifle cartridges so for this example we are going to first take a look at how the bolt functions when looking at the bolt it's important to note that it is actually a two-piece part so we have the bolt head up here and then the bolt body another important thing to note is the fact that the firing pin is not exposed like it what it was on the two straight blowback operated firearms that we looked at earlier you can see the firing pin in there and the fact that it is not currently exposed and if we look on the inside here we can see the firing pin and we'll know that it is actually attached to the bolt body not the bolt head it's on the inside of the bolt head but actually not part of it this is an important element of the functionality of the mg42 as well as a number of other lock breeched open bolt firearms the fact that the bolt is to separate or even more parts unlike what we've seen previously where the bolt is just a single piece with a fixed exposed firing pin if we watch as the bolt comes forward it's going to strip around from the belt much like our previous examples have stripped around from the magazine it's going to feed that round down into the chamber and then we're going to see the locking element of the design this is a roller lock design which is going to function somewhat similarly to the way a world or delayed blowback system would work but the main difference being that this is a lock reach design and as the bolt head comes forward we're going to see the rollers which are here this piece here are going to extend outward into this area that's attached to the barrel and once that has occurred the bolt has locked in place and what causes this to happen is just a simple camming action so if we look in here we'll see the slope surface here and we'll see a similar surface on the top edge and this is going to interact with the top and bottom of the roller so if we watch closely as the roller comes in at the moment it contacts that slope surface it's going to start to roll out until it gets to the point where it is now on a straight edge area and due to this surface here in the back that roller is now locked in place now you might have also heard faintly there the firing off of the cartridge well what happens with that if we watch the bolt from above as the bolt head locks in place it's going to stop moving forward it's going to stop its momentum but as we discussed earlier the bolt body is a separate piece so it's going to continue its momentum and drive forward and as it does so it's going to expose that firing pin and ignite the primer and the cartridge and then you have the firing you may be wondering why don't we have an exposed firing pin like what we had those other two examples we looked at and the reason for that is because those were straight blowback operate systems that do not have a lock breech system and we need to allow for that breech to be locked in we need the bolt and the barrel to be locked together before we fire the cartridge if there is an exposed firing pin the second we seeded that cartridge in the chamber it would fire we need a delay before that happens we need the rollers to come in and lock so we want the firing to occur after that has happened and that is the reason why we don't have an exposed firing pin and instead we have this multi piece bolt that we have and let's continue on and move on to the unlocking process so this being a short recoil operated system the barrel and bolt will travel together for a short distance which we can see happening right now and as they travel together the Bolton bear will remain locked as you can see the rollers still out and it's still being locked by this edge here on the barrel but as we move in there is a sloped surface on the receiver and as the barrel and bolt recoil to the rear that slope surface is going to cam the rulers in unlocking the barrel from the bolt and allowing the bolt to travel the rest of the distance to the rear and then allowing for action and ejection of the spent cartridge case let's back things up to the moment that the bolt is driving forward and feeding the cartridge into the chamber and take a look at the bowl internally so that we can see the firing pin and how it works so currently with the rollers and their innermost position they are holding the firing pin in between them back so the firing pin is attached to this wedge-shaped piece here which is prevented from allowing the firing pin to move forward because of the contact with the rollers but as the bolt moves forward and the rollers move outwards that blocking of the wedge is no longer occurring and at this moment we can allow the momentum of the bolt body to continue forward as the bolt head stops its momentum and this allows the firing pin to drive forward striking the primer so we can see that happen again there's the firing pin coming in and striking the primer and as the bolt and barrel recoil backwards the rollers are going to cam back in and this is going to force the wedge back due to the sloped surface here the wedge is going to be cam to back which is going to bring the firing pin back into its rear position and again unable to contact the primer and now we're going to focus on the trigger group and although there is going to be some differences with the other trigger groups we've seen so far the overall functionality is going to remain the same so we have the trigger here we have the sear which is in contact with the bolt and as we pull the trigger it's going to pivot the trigger which in turn is going to pivot the sear down and away from the contact with the bolt which is going to let the bolt come forward under the strength of the releasing tension of the recoil spring now a couple differences is the functionality of this metal loop here and also how the trigger acts upon this year so as we pull the trigger the trigger is going to pivot upon this point here there's a pin that goes through the frame of the firearm and through the trigger and the trigger is going to pivot upon that point now there's also another pin here and as we pull that trigger that pin is going to be driven upwards and as that pin is driven upwards it's going to push on the underside here of this part of this year which isn't going to turn pivot to see our upon this point where it is pinned through the frame pivoting this part of the sear down so we can see that in practice here as that is getting pushed up on by this pin you see are starting to pivot downwards now this metal loop is also important because as we fold the trigger it's going to pivot this part of the trigger down which is pinned to this metal loop and as this metal loop is pulled downwards it's going to cam along the end of the sear here and once it cams along enough it's going to go beyond this surface here on the sear once that happens this spring here is going to force the middle loop forward now the reason it does this is so the sear cannot come back up this surface here will catch the end of this year and prevent it from coming up this is a fully automatic firearm as long as we keep the trigger pulled this metal loop will keep the sear held down as we cycle the action and not a whole lot is going to happen here while we have the trigger held in the pin is going to keep this year held downwards by pushing up on this part of the sear and even at this point if we were to let go the sear here would still be held in place by this metal loop so let's go ahead and take a look at what happens when we let go of the trigger so so as we let go of the trigger right about this point we see the middle loop is going to come up and keep the sear held down even though we've let go of the trigger but as the ball comes past here you see it just kisses the top of the metal loop but as the bolt comes back that same part that kissed the top of the metal loop because of the way that the metal loop is shaped here and the way the bolt was shaped here before just kiss the top of the metal loop but now because we have the angle up like this and we have a different area here instead of just kissing it it's going to contact it and bring it back this is going to break its contact with the sear allowing the sear to come back up and once the bolt comes back forward this year is going to catch it a little bit different and functionality but overall the same once we let out the trigger the seer is going to come up ready to catch the bolt when it comes around again the last example we're going to look at is the BA R which is something of an odd duck which we're going to cover not only because it uses a gas-operated open bolt action but it also shows that although the open bolt action is a simple concept it can be designed to be quite complex if you put your mind to it and the complexity is such with the var that even identifying the main components we're going to be focusing on can be a little bit of a challenge first starting off with the bolt it consists of a lot of parts so we have this part here and all of this stuff up here all the way up to here this is all part of the bolt and then the bolt is attached to the piston here this is a gas-operated system so it does have a long stroke gas operate system and here's the piston which is directly attached to this part of the bolt or bolt carrier perhaps you would call it then we have the trigger group down here with the trigger here and we have a number of mechanisms going on over here and then we have the sear here with its contact with the bolt ear or both carrier if you want to call it that the bolt itself is an articulated piece consisting of multiple parts that go all the way up to here as we did with the mg42 we're going to first start off focusing on the functionality of the bolt and just like with the mg42 this is a lock breech design so currently the firing pin is not exposed and said it's in side the internal parts of the bolt head and as we cycle the bolt forward it's going to strip the next round from the magazine and feed it into the chamber now once the bolt head comes to rest on the barrel it's going to stop its momentum but the bolt carrier down here is going to continue forward and as it does so it's going to force this articulated part of the bolt which I wanna just call the arm upwards and as that occurs is articulated arm is going to fit into a recess and the receiver and butt up against the shoulder right here and this is what locks the bolt in place if I currently try to force the bolt head to the rear this articulated arm would prevent it because of its contact with the shoulder so as the bullet continues forward the firing pin is going to be driven into the primer and the base of the cartridge which is going to ignite the propellant in that cartridge and then the bolt carrier is going to start to move to the rear and this is due to the expanding gasses diverting into the gas tube here which is going to force the piston to the rear and as it does so it's going to push the bolt carrier back as the bolt carrier is pushed back it's going to start pulling down on the articulated arm and once the articulated arm is pulled down enough so that it breaks contact with the shoulder and the receiver the bolt head can start moving backwards and as it does so it's going to extract and then eject you spent cartridge case and once the bolt carrier has traveled back far enough it's going to be caught by the seer which we can see about to happen now the seer is catching the bolt carrier and the seer interestingly enough is attached to the spring-loaded here area here which is going to soften the shock of catching the heavy bolt carrier let's now look at how the firing pin functions and this is where the BA R is somewhat of an odd duck compared to the other open bolt firearms we've looked at as it functions somewhat like a hammer fired action in that the bolt itself kind of acts like a hammer striking the firing pin and we can see that happening as the arm here is articulating upwards this part of the bolt is coming forward and once it comes forward it's going to strike the back end of the firing pin and it's this blow that drives the firing pin forward into the primer so this is acting like a hammer on a hammer fired action coming in and striking the firing pin very unlike the other open bolt actions we've seen so far so very unique and interesting design I discussed earlier in the video that the program I use would cause me some issues and demonstrating some of the functionality of these firearms and one limitation it has with certain firearms is that certain elements of the function that firearm are not very well animated or the animations are missing or the timing of those animations are off to what they would be in the true functionality of the firearm and the trigger group actually has a couple different issues the first issue is the fact that the pulling of the trigger is not animated at all no matter how much I slow down the program when I press the fire button it just jumps straight from the trigger being in its forward position to it's fully rear most position having been fully pulled there's just no animation in between that so unfortunately I can't show you what happens as the trigger is pulled and sit dead I'm just going to have to describe it to you another issue we'll get into a little bit later is the fact that the timing of some of the movement of the parts is incorrect chiefly out of laziness so that the animations of the operation of the firearm would fit more easily together during fully automatic fire and because the current animation loop I have is only a single shot the time is going to be off any case let's go ahead and discuss what happens when the trigger is pulled so as the trigger is pulled the trigger is going to pivot and as it pivots it's going to bring this piece here connect to the trigger up and as this piece moves upward it's going to contact this piece here and that is going to force this arm here to pivot downwards and we can see on the other side here's the arm pivoted downwards now the importance of this arm is not that it acts upon the sear it actually doesn't instead what it does is it fits in between the Ciera and blocks contact with this plunger here and if we zoom out here we can see this plunger is spring-loaded well what happens when this piece breaks contact with this plunger as it pivots down is it allows the plunger to act upon the sear now currently this year is pushed down and it is not actually in contact with the bolt carrier the bull carry just hasn't started moving forward yet what happens is this plunger pushes forward and acts upon the sear and because of this slope pushes it downwards as the plunger moves in it pushes down on the sear and once this year breaks contact with the bolt carrier the bolt carrier is free to move forward now I've zoomed out quite a bit here so that we can get full view of the spring-loaded plunger as its functionality is important to the operation of the trigger group itself so as the bullet comes forward it's going to do its thing and then it's going to come to the rear now as it comes to the rear the bolt carrier is going to force the plunger backwards and as it does so the seer can move back up because the plunger is no longer acting upon it and at this point the seer we'll grab the bolt carrier as it comes forward even if we just the trigger once and then let it go this would still occur because remember the trigger does not actually act upon the sear it only allows the plunger to act upon this year now when the bolt carrier strikes the plunger the plunger punches this piece here which is going to act upon this spring so the spring that acts upon the plunger does so indirectly due to the contact of this part and once the bolt carrier punches the plunger backwards this piece is going to be forced down and once that momentum is overcome by the tension of its spring it's going to start to force this piece back forward and then eventually it's going to contact the plunger and force the plunger forward again now you can see in this animation the sea are being driven down as it normally would be if we continue to hold the trigger and as we have done but because this animation loop contains the animation for just a single shot we're going to see some frankly in correct timing happen so what we're going to see happen is the trigger get let out which is going to cause this piece here to start to move up now you might see the sear coming up this normally would not happen as you're letting out the trigger as the trigger does not act upon the sear what actually is happening is this piece in the middle is starting to push back on the plunger removing its contact from the sear as you can see with this piece with the trigger let out and this piece allowed to be in its uppermost position it's preventing the direct contact of the plunger with the sear and again it's this plunger that forces this year down why is this animation incorrect because if we had not let out the trigger what would have happened as this piece comes back forward to strike the plunger is the plunger would have acted upon the sear as we see animated and once this year would drop like this what's keeping the bolt carrier from moving forward nothing it would move forward so it's this plunger that is responsible for the automatic fire as it acts upon the sear again the bolt carrier is allowed to move forward again because the seer is tripped as long as we keep the trigger held in that would continue if we let out the trigger before the plunger struck this year this piece here this arm would prevent that contact of the plunger and the firearm would stop firing the bolt carrier would not move forward because this year would not let it go but this animation is incorrect because it shows the timing wrong it shows this piece coming up after the fact which would not prevent the seer from tripping the bull so if this animation were to be correct technically the bolt would have gone forward again then come back and this piece being in the way of the plunger the sear would not have tripped that would have been the correct animation but they didn't do it that way and the reason they didn't do it that way will demonstrate in a little bit here and what I'm going to do is I'm going to end the current animation loop and start a new one but in this new animation loop I'm going to keep the trigger held down and watch what happens with the animation and how it differs so as I keep the trigger held down we see the bolt cycling as it normally would and honestly this is probably a little too slow we see the plunger come up act and then the bolt comes forward so now the animation is correct because the plunger is what is tripping the sear as it normally would be so how is this any different than the animation loop that I showed you before it isn't all they have done to change the animation loop or the last shot in a cycle if I let go of the trigger now it just append a little bit of an animation with the trigger resetting even though that animation is entirely incorrect it makes it a lot easier though to loop the animations together because all you have to do is just trim off that little bit at the end to get a correct fully automatic cycle with all that being said let's go ahead and fire this thing in full auto which is the only way that this firearm fire is honestly and empty out a full magazine now I've sped things up quite a bit so that it's only half speed and there we see one element of the function of an open-bolt firearm and that when you have fired off the last shot the bolts going to still come back and then forward again but because you're not feeding in another cartridge and firing that off there's no recoil energy to send the bolt back again so it will stop in the forward position which is actually technically the opposite of what you often see in a closed bolt action where the bolt would be locked back on the last shot now there is an actual mechanism and a closed bolt firearm to get it to do that as that's not naturally what it would do but with an open bolt firearm it will do that regardless it will come forward like this so when you go to reload you're going to have to bring the bolt back and then insert a fresh magazine before you can fire again now let's talk about the strengths and weaknesses of the open bolt action starting off with the strengths as we saw with the Sten in the first example an open bolt design can be super simple as the bolt delivers the energy to ignite the primer of the cartridge a hammer that strikes a firing pin or a striker that moves inside the bolt is no longer required this means less moving parts and less machining processes to manufacture an open bolt firearm keeping costs low the simplest open bolt firearms are so simple is something you can realistically make yourself with a little bit of tool handling skill the proper tools and a trip to the local hardware store for most of the parts this is why I have seen a few books with titles something like how to build a submachine gun in the comfort of your own home the main obstacle of building an open-bolt firearm yourself is building a magazine which if you design the firearm to accept already existing magazines you can circumvent that issue and rifling a barrel which is why all of the books I have seen on the subject have you building a smoothbore firearm the problem with the smoothbore barrel is that the modern factory produced ammunition you would use is not designed to be fired through a barrel without rifling and would be horribly inaccurate another strength especially for military purposes is the fact that an open-bolt firearm is less likely to cook off around after continuous firing has made the gun very hot as it keeps the action open thus allowing for better heat dissipation and does not hold a round in the chamber like a closed bolt action would another possible strength depending on how you look at it is the fact that the trigger group is naturally inclined to fire fully automatic with the trigger having to be specifically designed to allow for semi-automatic fire which is the exact opposite thing you find in a closed bolt action which is inclined to fire and semi-automatic mode moving on to the weaknesses which are many fold chief among which is the delay that occurs between the pulling of the trigger and the actual firing of the cartridge all the time it takes for the bolt to travel forward feet are rounded the chamber and then fire the cartridges time that you as the shooter have to hold the firearm on target making accuracy difficult when being fired one shot at a time barring in fully automatic can overcome this any accuracy to a degree by allowing the shooter to walk the fire on target but this downside is what prevented hunting arms for instance ever adopting an open bolt design with any amount of success a potential concern is the fact that all that holds the bolt back in many open bolt designs is contact with the seer potentially being a safety hazard if the contact was inadvertently broken by the firearm being jarred by a sharp impact for instance if the firearm was dropped another weakness is the fact that the open action of an open bolt design is a vulnerable to the ingress of dirt and other various substances you do not want any action requiring special care to be taken and possibly requiring the action be carried closed and not bringing the bolt back until the firearm is ready to be fired both to prevent dirt from getting in but also as a safer way to carry the firearm if there is no round in the chamber unfortunately as interesting as open bolt firearms are it is not something many of us the United States will likely ever encounter at least not someone of my age or younger in any case I hope you have enjoyed the video and found it informative this is mouse gunner signing out

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Views: 180,881

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Keywords: firearms

Id: UyLKNS7mUrg

Length: 48min 39sec (2919 seconds)

Published: Fri Feb 05 2016