socalbeachbum
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Can someone explain the term please and the opposite, 'fires from a closed bolt'?
'it fires from an open bolt' - what does this mean?
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typically on machine guns the bolt is open and the firing pin is fixed to it. the trigger just holds the bolt back. when you pull the trigger, it goes forward, picks up a cartridge and goes boom
in a closed bolt, the bolt is closed on a round in the chamber and the trigger holds the hammer back. pulling the trigger releases the hammer and it goes boom, then cycles
in a closed bolt, the bolt is closed on a round in the chamber and the trigger holds the hammer back. pulling the trigger releases the hammer and it goes boom, then cycles
rcmodel
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It means the bolt is held open all the time except when the trigger is pulled.
It then flys shut, chambers a round, and fires it before opened and staying back again.
It is typically used on sub machine guns for simplicity, and big machine guns to keep a round from cooking off in the chamber of a hot barrel.
It also aids in barrel cooling a little.
rc
It then flys shut, chambers a round, and fires it before opened and staying back again.
It is typically used on sub machine guns for simplicity, and big machine guns to keep a round from cooking off in the chamber of a hot barrel.
It also aids in barrel cooling a little.
rc
4thPointOfContact
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What ^they^ said, but just want to add that the ATF looks at open bolt guns like the average person looks at a coiled up rattlesnake. It's not biting now, but ya just know it's going to. By which I mean that the ATF won't approve for production any open bolt pistol, rifle, or shotgun even if said firearm has no magazine and is a single-shot.
AK103K
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Open bolt guns while simpler, have their own issues, especially when it comes to safety issues.
First and foremost, to shooters who are accustomed to closed bolt guns, the gun looks to be "safe", with the bolt locked back. When in fact, its ready to go.
Making them safe from cocked requires you to drop the mag, prior to allowing the bolt to go forward. Sounds a little silly, but you'd be amazed at how many people screw this up.
Many of the open bolt guns tend to be more prone to firing if dropped or jarred. The bolt doesnt even have to be cocked for this to occurr. If it wasnt "locked" in the forward position, in some circumstances, it can move rearward enough toy strip a round and fire it.
There is also the worry of your hand slipping while cocking, before the bolt locks back, and the bolt moving back forward, and stripping a round and firing it. Ive seen this happen on a number of occasions, and its very important youre paying attention to whats going on when youre charging them. If your finger is on the trigger when it occurs, it just only gets worse, and in a hurry.
First and foremost, to shooters who are accustomed to closed bolt guns, the gun looks to be "safe", with the bolt locked back. When in fact, its ready to go.
Making them safe from cocked requires you to drop the mag, prior to allowing the bolt to go forward. Sounds a little silly, but you'd be amazed at how many people screw this up.
Many of the open bolt guns tend to be more prone to firing if dropped or jarred. The bolt doesnt even have to be cocked for this to occurr. If it wasnt "locked" in the forward position, in some circumstances, it can move rearward enough toy strip a round and fire it.
There is also the worry of your hand slipping while cocking, before the bolt locks back, and the bolt moving back forward, and stripping a round and firing it. Ive seen this happen on a number of occasions, and its very important youre paying attention to whats going on when youre charging them. If your finger is on the trigger when it occurs, it just only gets worse, and in a hurry.
Arizona_Mike
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As far as cooling is concerned, while there is a small improvement in air circulation, the main advantage is the chamber can be allowed to get hotter without the danger cooking off a chambered round.
The other advantage is primer pre-ignition. The breech is still closing as the round is being fired allowing a blowback bolt/bolt carrier to be about half the weight it needs to be for a closed-bolt blowback.
The main disadvantage is accuracy. Both in terms of lock time and having heavy moving parts changing the point of aim between the sear release and ignition.
Mike
PS. Adding to what AK103K said, another issue is weak ammo (and/or a dirty gun) moving the bolt far enough back to pick up a new round but not far enough to engage the seer (this is usually a significant distance to allow the bolt to accelerate before it reaches the magazine) causing the gun to "run away". If this happens, you are in for a bit of a ride, exp. with a drum or belt
I like to test new ammo brands with a small number of rounds loaded.
The other advantage is primer pre-ignition. The breech is still closing as the round is being fired allowing a blowback bolt/bolt carrier to be about half the weight it needs to be for a closed-bolt blowback.
The main disadvantage is accuracy. Both in terms of lock time and having heavy moving parts changing the point of aim between the sear release and ignition.
Mike
PS. Adding to what AK103K said, another issue is weak ammo (and/or a dirty gun) moving the bolt far enough back to pick up a new round but not far enough to engage the seer (this is usually a significant distance to allow the bolt to accelerate before it reaches the magazine) causing the gun to "run away". If this happens, you are in for a bit of a ride, exp. with a drum or belt
I like to test new ammo brands with a small number of rounds loaded.
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bangswitch
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Arizona_Mike
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Neat gun. Given the fact that it is a single shot it probably does not even have to be counted as a "grandfathered" open bolt. Single shots are allowed to have things like electronic ignition which are absolutely verboten on auto-loaders.
PS. I guess not totally verboten (but probably needs approval): http://www.thefirearmblog.com/blog/2014/12/19/electronic-arms-1022-bullpup-electric-trigger/
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In a closed bolt semiauto the bolt is closed before firing and the trigger controls the firing pin.
In an open bolt semiauto the bolt is open and all the way back before firing. When the trigger is pulled, the bolt goes forward, strips a cartridge from the magazine, chambers it and a small projection on the bolt face fires it as soon as the cartridge is fully chambered.
Simple to make, very rugged, prevents cook offs in machine guns.
Drawbacks? In a closed bolt gun the trigger only has deal with enough spring weight to operate the firing pin / hammer and most of the spring force necessary to operate the action is taken up by the bolt.
On an open bolt gun the entire spring weight necessary to operate the action has to be handled by the trigger. This requires more engagement surface to handle the load. This makes for a heavy, creepy trigger. Not a problem for machine guns where pinpoint accuracy is not required or even desirable, but a real disadvantage for sporting arms.
In an open bolt semiauto the bolt is open and all the way back before firing. When the trigger is pulled, the bolt goes forward, strips a cartridge from the magazine, chambers it and a small projection on the bolt face fires it as soon as the cartridge is fully chambered.
Simple to make, very rugged, prevents cook offs in machine guns.
Drawbacks? In a closed bolt gun the trigger only has deal with enough spring weight to operate the firing pin / hammer and most of the spring force necessary to operate the action is taken up by the bolt.
On an open bolt gun the entire spring weight necessary to operate the action has to be handled by the trigger. This requires more engagement surface to handle the load. This makes for a heavy, creepy trigger. Not a problem for machine guns where pinpoint accuracy is not required or even desirable, but a real disadvantage for sporting arms.
AK103K
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I havent found that to be the case. My MAC's trigger was pretty decent, and not at all heavy. My buddies MP40's trigger is actually almost too light, and one gun I really wouldnt want to drop. Come to think of it, most of the open bolt SMG's Ive shot, werent bad at all.
Now, my MP5 had a typical HK trigger, and was the heaviest of the bunch. Not that they are bad triggers, they arent, just not what most Americans seem to think a trigger should be.
USAF_Vet
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Your muzzle loader isn't considered a firearm by ATF so no, it doesn't count.
basically with a closed bolt, you have a striker or hammer, which is a small amount of mass, striking the firing pin.
with an open bolt design, the WHOLE freakin' bolt comes shooting forward with the firing pin protruding when you pull the trigger.
which one do you think will have less lock time?
the benefit of course, is that the open bolt keeps the breach open to cool when the shooter is not firing. This is great if you have selective fire, but of course, most of us don't, therefore a semi that fires from an open bolt, is well, going to kind of suck.
with an open bolt design, the WHOLE freakin' bolt comes shooting forward with the firing pin protruding when you pull the trigger.
which one do you think will have less lock time?
the benefit of course, is that the open bolt keeps the breach open to cool when the shooter is not firing. This is great if you have selective fire, but of course, most of us don't, therefore a semi that fires from an open bolt, is well, going to kind of suck.
AK103K
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Once you get used to shooting them, I think you'd be surprised at what you can do with them. The bolt moving when the trigger is released is a little disconcerting at first, but that soon goes away.
No doubt the hammer fired closed bolts are more accurate from a pure accuracy/target/group shooting standpoint, but for more realistic type shooting, the open bolts are more than capable, if you are.
Ive shot 3-4" offhand groups at 25 yards with both an MP40 and a Swedish M45 "single shot" with no troubles. If you take the time to shoot them deliberately at longer ranges, they can actually do quite well.
Most peoples experience with these type guns these days is close range, and they arent there for single round bursts.
kBob
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What most everyone else said.
As to drop safety......several designs of smg have means of locking the bolt forward. The MP-40 for instance has a movable bit on the cocking handle that can be pressed inwards towards the gun to lock the bolt forward and the receiver has a J shaped cocking slot that allows one to put near max spring pressure on the bolt while it resides in the short leg of the J slot as an open bolt safety.
One of the Uzi design features is a grip safety that when not depressed stops the bolt from rearward travel.
Those old Madsen clam shell guns like the M1946 had a grip safety on the magazine housing that also blocked rearward travel when not depressed. This is why they were sometimes taped down by wraps of tape in some South American police forces, to allow one handed firing in an emergency. If you do not know the guns of the series (M1953 I believe was the last of), just watch about any episode of the original season "Mission Impossible" TV show.
Even some late model Sten guns have a safety where the cocking handle can be pushed all the way through the bolt to engage a hole on the opposite side of the receiver like an old Savage 6 .22 rifle.
While accuracy with the open bolt guns in standing unsupported positions is generally no where near as good as with similar closed bolt guns, (not always so, see 1980s closed bolt pistol caliber carbines based on SMGs but with 16 inch barrels) Some are capable of more than acceptable accuracy from supported positions. Those fancy lyman rear sights on 1921 an 1928 series Thompsons are not a waste at all.....if you fire from a supported position or a good prone position.
-kBob
As to drop safety......several designs of smg have means of locking the bolt forward. The MP-40 for instance has a movable bit on the cocking handle that can be pressed inwards towards the gun to lock the bolt forward and the receiver has a J shaped cocking slot that allows one to put near max spring pressure on the bolt while it resides in the short leg of the J slot as an open bolt safety.
One of the Uzi design features is a grip safety that when not depressed stops the bolt from rearward travel.
Those old Madsen clam shell guns like the M1946 had a grip safety on the magazine housing that also blocked rearward travel when not depressed. This is why they were sometimes taped down by wraps of tape in some South American police forces, to allow one handed firing in an emergency. If you do not know the guns of the series (M1953 I believe was the last of), just watch about any episode of the original season "Mission Impossible" TV show.
Even some late model Sten guns have a safety where the cocking handle can be pushed all the way through the bolt to engage a hole on the opposite side of the receiver like an old Savage 6 .22 rifle.
While accuracy with the open bolt guns in standing unsupported positions is generally no where near as good as with similar closed bolt guns, (not always so, see 1980s closed bolt pistol caliber carbines based on SMGs but with 16 inch barrels) Some are capable of more than acceptable accuracy from supported positions. Those fancy lyman rear sights on 1921 an 1928 series Thompsons are not a waste at all.....if you fire from a supported position or a good prone position.
-kBob
I can't comment on the guns mentioned, but I do have several open bolt 22s (Gevarm E1, Winchester 55, Voere 2005 and a BSA Ralok) and they all have heavy and creepy triggers to one degree or another. It's possible to smooth things so that the triggers are tolerable, maybe even decent, but you're not going to get the top notch trigger of a Winchester Model 52 out of one. There's just no way to get around the extra spring weight the trigger on an open bolt gun has to deal with.
AK103K
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Theres no doubt they are different, I just dont see them as "bad". Most of my experience with open bolt guns, has been with former military guns, and they really all have been decent, some downright nice, and some even downright scary.
It seems to me, at least since the internet has been around, many people seem to be overly trigger sensitive anymore. I used to get complaints about my HK rifle and SMG triggers all the time. They too are "different", but once you get used to them, are not bad at all. I had no troubles shooting them as well as my M1A's, M1's, etc.
If I were to complain about any of them, it would be the issue M16/AR triggers. They are for the most part, the crunchiest triggers I shoot. Still, they arent a problem, they are just what they are.
I shoot all types of guns and triggers, and came to the realization pretty early on, that if you can shoot DA handguns well, in DAO, you can pretty much shoot everything without issue. I think a lot of the complaints you hear, come from those who are stuck on unrealistic or tuned triggers, and cant seem to shoot anything else.
Unless there is something obviously wrong with them, which is rare these days, I dont bother with messing with triggers anymore. Most are fine out of the box.
It seems to me, at least since the internet has been around, many people seem to be overly trigger sensitive anymore. I used to get complaints about my HK rifle and SMG triggers all the time. They too are "different", but once you get used to them, are not bad at all. I had no troubles shooting them as well as my M1A's, M1's, etc.
If I were to complain about any of them, it would be the issue M16/AR triggers. They are for the most part, the crunchiest triggers I shoot. Still, they arent a problem, they are just what they are.
I shoot all types of guns and triggers, and came to the realization pretty early on, that if you can shoot DA handguns well, in DAO, you can pretty much shoot everything without issue. I think a lot of the complaints you hear, come from those who are stuck on unrealistic or tuned triggers, and cant seem to shoot anything else.
Unless there is something obviously wrong with them, which is rare these days, I dont bother with messing with triggers anymore. Most are fine out of the box.
jad0110
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If one ever has the opportunity to shoot an open bolt gun for a first time, this bears remembering. Here's a video from Hickock45 illustrating the point:
https://www.youtube.com/watch?v=POnZTsqM79k
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