Functioning Of the Semi-Automatic Pistol

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Thread: Functioning Of the Semi-Automatic Pistol

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    Functioning Of the Semi-Automatic Pistol

    Functioning Of the Semi-Automatic Pistol

    While I was teaching a Firearms Instructor In-Service course today the subject of the cycle of operation of a Semi-Automatic Pistol came up. There were 15 Firearms Instructors in the room, with over 200+ years of Instruction experience among them. The answers I got shocked me, the below is the information I gave out in class. I thought I would post this and see what type of response it got.

    Self-loading or auto-loading firearms fall into three distinct categories when it comes to their modes of operation. All have the similar characteristics of using the energy generated by the firing of a cartridge to actuate the action and effect the extraction and ejection of the spent cartridge case and then proceed to load a fresh round from the ammunition source. They differ in how they make use of this energy and on what type of energy they rely upon.

    Recoil operated: firearms are generally closed breech or closed bolt weapons that use a mechanical lock to keep the gun in-battery at the moment of firing. The sheer recoil pushes back on the slide or bolt which will then unlock the mechanism and begin the cycle of extraction, ejection and feeding. An example of recoil operated firearm is the Glock or Model 1911.

    Gas operated: firearms use the immense pressure generated by the burning powder or propellant to actuate a piston which reciprocates to do the cycling of ammunition. The M-16 rifle is a gas operated firearm. Though mostly used in rifles where greater pressures are achieved, some gas operated pistols are also manufactured. The desert Eagle is one.

    Blowback: operated firearms are simple and oftentimes open-bolt firearms. This means that there is no mechanical locking of the bolt and it is only the inertia of the bolt, the weight of the slide, and the spring tension which keeps it in place at the moment of firing. The cartridge literally blows back on the bolt to actuate the action. The advantages are high cyclic rates without the risk of a cook-off and mechanical and manufacturing simplicity. The major drawbacks are a lowered standard of consistency and accuracy. Popular open-bolt guns are the Uzi and Ingram Mac 10 which are meant for close-in combat where the cyclic rate of fire is needed more than bulls-eye accuracy. Smaller caliber handguns which produce insufficient energy to unlock a locking bolt (.380 cal. and smaller) are examples of blowback operated firearms of a closed bolt design.

    Note: While the revolver is indeed a repeater in that you can fire more than one round without reloading, it is not a self loading firearm as in fact the chambers have all been previously loaded by the operator before the cylinder was put into place.


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    Nice informative post on semi-automatic pistols.
    Very clear and easily understood.
    Many new members here will find the information helpful.

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    VIP Member Array boricua's Avatar
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    Although, the info is way over my head (too technical for me), it does make sense...
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    It's interesting because if I'd been asked the difference btw 'recoil' operated and blowback, I'd probably have gone...uh, huh? I've never stopped to think about what I'd call 'passive' locking and blowback. I'd have described the 1911 as a blowback weapon. I stand informed.

    So, there must be a few 'hybrid' or quirk mechanisms out there that stand in the gray area...the 1928 Thompson...not the 28A1, but the first one with its so-called 'adhesion' locking scheme. At least in the designer's mind if no where else, it was locked breach, but only weirdly so. Blowback or recoil operated?

    Also interesting though is the use of the word 'piston'. There's a big difference between a real piston-operated gas system and say, the M16 which has no piston at all. So, there are only two weapons I know first-hand that use pistons, and I'm sure there many, many others. The first is the FN 1949 rifle with a no-kidding piston, and the other is the Finnish Lhati anti-tank rifle, again, a no-kidding gas-operated piston.

    I think the Desert Eagle is NOT a piston operated system, correct? It operates just like the M16 genre of systems.

    Anyway, I'd be more interested in your 'horror' answers. My favorite is the 'bullet designed to tumble'. A legend that lives to this day, feverishly defended, no matter how many engineers are pumped out of colleges and universities.

    Oh, not to freak out the citizens, but I think locked vs unlocked is your big point of difference, then the next differentiaror is HOW do I unlock the locked systems. Sure, gas operated systems use gas pressure to cycle the loading, extraction and ejection...no argument. How these systems lock and get unlocked it quite a bit more interesting. That would bring up just a few families which are markedly distinct: a rotary lock on the bolt (desert eagle, M16), a bolt camming into lock with an upper receiver or slide (FN, AK, 1911, almost everone) and the roller lock of HK.

    Anyway, I THINK (and I could be quite wrong, I'm an old guy) this would highlight M1911 design as the 99.9% chairman of the board when it comes to locking up and cycling. Blowback being limited largely to .22 autos, I'd say.
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    Very well explained. I'm more curious what the other instructors in the room had said that shocked you but I guess thats another post.
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    Quote Originally Posted by Bongo Boy View Post
    ...the 1928 Thompson...not the 28A1, but the first one with its so-called 'adhesion' locking scheme. At least in the designer's mind if no where else, it was locked breach, but only weirdly so. Blowback or recoil operated?...
    Blowback. Even if the Blish-system "lock" worked, it still would've been a "retarded blowback" device.
    Considering the silliness of the Blish system, I'd say that "retarded" was the appropriate word.
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    M-14

    Quote Originally Posted by Bongo Boy View Post
    So, there are only two weapons I know first-hand that use pistons, and I'm sure there many, many others. The first is the FN 1949 rifle with a no-kidding piston, and the other is the Finnish Lhati anti-tank rifle, again, a no-kidding gas-operated piston.
    I believe these are some more examples; the M-14 Springfield M1A us a pistion and operating rod, my M-1 carbine variant used dual operating rods and I believe the Garand has an operating rod and piston similar to the M-14.
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    Quote Originally Posted by bbqgrill View Post
    I believe these are some more examples; the M-14 Springfield M1A us a pistion and operating rod, my M-1 carbine variant used dual operating rods and I believe the Garand has an operating rod and piston similar to the M-14.
    Yeah I'm sure there are many more. Didn't know that about the M14, either. I know this is getting off-topic kinda, but in all or most of the systems with gas rods, does the operating rod only move a very short amount relative to the bolt/carrier? My understanding, which is so often wrong, is that the operating rod in at least some weapons only moves a wee bit (like less than 1/4" or something). Izzat true?
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    Helpful fundamental post Tom. Well done.

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    I think the Desert Eagle is NOT a piston operated system, correct? It operates just like the M16 genre of systems.
    The M16 isn't operated with a piston either. They can be modified to be though. Both systems fall under "gas operated". Gas pistons just tend to reduce fowling in the actions.
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    AFAIK

    Quote Originally Posted by Bongo Boy View Post
    Yeah I'm sure there are many more. Didn't know that about the M14, either. I know this is getting off-topic kinda, but in all or most of the systems with gas rods, does the operating rod only move a very short amount relative to the bolt/carrier? My understanding, which is so often wrong, is that the operating rod in at least some weapons only moves a wee bit (like less than 1/4" or something). Izzat true?
    Specifically with the m14/M1A the piston stroke is short far less than what the bolt moves, But, the two groups are not attached the piston just pushes the op rod and bolt, inertia does the rest until the action spring overcomes the inertia and returns the gun to battery. In short yes, you are correct.
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    Member Array Randy's Avatar
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    Quote Originally Posted by DCJS Instructor View Post
    Functioning Of the Semi-Automatic Pistol

    While I was teaching a Firearms Instructor In-Service course today the subject of the cycle of operation of a Semi-Automatic Pistol came up. There were 15 Firearms Instructors in the room, with over 200+ years of Instruction experience among them. The answers I got shocked me, the below is the information I gave out in class. I thought I would post this and see what type of response it got.

    Self-loading or auto-loading firearms fall into three distinct categories when it comes to their modes of operation. All have the similar characteristics of using the energy generated by the firing of a cartridge to actuate the action and effect the extraction and ejection of the spent cartridge case and then proceed to load a fresh round from the ammunition source. They differ in how they make use of this energy and on what type of energy they rely upon.

    Recoil operated: firearms are generally closed breech or closed bolt weapons that use a mechanical lock to keep the gun in-battery at the moment of firing. The sheer recoil pushes back on the slide or bolt which will then unlock the mechanism and begin the cycle of extraction, ejection and feeding. An example of recoil operated firearm is the Glock or Model 1911.

    Gas operated: firearms use the immense pressure generated by the burning powder or propellant to actuate a piston which reciprocates to do the cycling of ammunition. The M-16 rifle is a gas operated firearm. Though mostly used in rifles where greater pressures are achieved, some gas operated pistols are also manufactured. The desert Eagle is one.

    Blowback: operated firearms are simple and oftentimes open-bolt firearms. This means that there is no mechanical locking of the bolt and it is only the inertia of the bolt, the weight of the slide, and the spring tension which keeps it in place at the moment of firing. The cartridge literally blows back on the bolt to actuate the action. The advantages are high cyclic rates without the risk of a cook-off and mechanical and manufacturing simplicity. The major drawbacks are a lowered standard of consistency and accuracy. Popular open-bolt guns are the Uzi and Ingram Mac 10 which are meant for close-in combat where the cyclic rate of fire is needed more than bulls-eye accuracy. Smaller caliber handguns which produce insufficient energy to unlock a locking bolt (.380 cal. and smaller) are examples of blowback operated firearms of a closed bolt design.

    Note: While the revolver is indeed a repeater in that you can fire more than one round without reloading, it is not a self loading firearm as in fact the chambers have all been previously loaded by the operator before the cylinder was put into place.


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    Great information to share. Thanks for posting.

    I do have one suggestion though, if I may.

    I know the best ideas are always someone else's and there's no sense in duplicating efforts for works that have already been satisfactory completed. In that respect, when utilizing someone else's work (copied verbatim in this case), please give the author(s) the credit due.

    Randy

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    Randy,

    I believe what I said was :

    While I was teaching a Firearms Instructor In-Service course today the subject of the cycle of operation of a Semi-Automatic Pistol came up. There were 15 Firearms Instructors in the room, with over 200+ years of Instruction experience among them. The answers I got shocked me, the below is the information I gave out in class. I thought I would post this and see what type of response it got.

    I do not know the Author to give credit. The information came from a Law Enforcement Handgun Instructor Course Lesson Plan.

    Most folks on this sight may not have access to this type of good information. So I thought I would share.

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