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Thread: Locktime

  1. #16
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    I've always preferred to use the term 'shot generation time' when referring to airguns.

    Just saying.
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  2. #17
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    Quote Originally Posted by RichardH View Post
    Locktime is a function of the firearm itself, what happens after the pin hits the primer is a function of the cartridge.

    Very seperate issues
    But this relates only to cartridge guns. Do other projectile weapons not have a locktime?
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  3. #18
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    Quote Originally Posted by Turnup View Post
    But this relates only to cartridge guns. Do other projectile weapons not have a locktime?
    Airguns don't technically even have a lock...

    gunlock

    noun

    a mechanism by which the charge of a gun is exploded.
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  4. #19
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    Quote Originally Posted by bezzer View Post
    What is your problem, it's not MY definition, just search lock time definition and you will find they all refer to hammer to propellant NOT ltrigger to barrel exit, nice article ishttp:// http://www.chuckhawks.com/locktime.htm which does include some timings.
    Of course it's hard to measure by us mere mortals but certainly possible, it's just as hard to measure the extra milliseconds for the bullet/pellet to exit.
    A lot of the time it is not measured anyway but improvements made that will speed it up, e.g. I've recently regged my AA400 and also made a longer faced hammer, lighter and delrin bushed, to shorten the stroke. This of course will shorten the time between pulling the trigger and hitting the valve, my locktime has therefore decreased, by how much I don't know or care but apparently every little helps in target shooting not that you'd know watching me
    The referenced article starts with a definition but which does not cite any authority for that definition. OK Chuck has at least given a basis for his subsequent statements so we understand what he is talking about. This does not constitute a definition with wider application beyond that one article. There seem to be few references to locktime in any scientific sense out there

    I can easily start a timer on trigger break and stop it on projectile emergence, using an unmodified firearm. Agreed that this introduces some difficulty wrt MV and barrel length., but it is measurable and capable of producing standardised (and therefore comparative) measurements by controlling barrel length and MV.

    Any other (of the may possibilities I have offered in posts above) would require modification of gun or cartridge or both and as such starts to become of questionable use, for example hammer to "propellant" would require some means of detecting "propellant" which did not modify in any way the behaviour of the propellant. I can conceive no way to do this without intruding into the cartridge or chamber and thus risk modifying the behaviour. [BTW a very slow burning propellant would affect the perceived locktime but probably not show up in the definition "hammer to propellant"] It seems to me that the time between trigger break and movement of the projectile is the most interesting and practically useful definition - problem is it is hard to measure - high speed x-ray perhaps? Does such a thing exist (I do not mean flash x-ray, which does exist, but something capable of capturing a series of images over the critical period)

    We can all make comparative judgements regarding the differences between "locktime" of various devices and in a general sense I thing we all understand what is meant, but I sincerely do not believe it is capable of a definition which allows proper measurement, without which we are all just waving our arms. When people talk about locktime we all understand that we are talking about how long it takes to happen but I think we are far from clear what "it " is. Does a crossbow have a locktime?

    From all of which I conclude that locktime is not well defined and can mean just whatever you want it to.
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  5. #20
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    Definition
    The term lock time refers is the time that elapses between the "tripping" of a gun's trigger and the ignition of the powder or propellant that drives the projectile(s) downrange.

    Lock time is so named because early firearms employed a lock, which contained almost all of the mechanical moving parts required to fire the gun. Once released by the trigger, the lock allowed the hammer (which was attached to it) to fall and ignite the powder charge and thus fire the gun.


    This takes time, and during that time the gun may move off target; thus the shorter the lock time, the better. All other things being equal, shorter lock times allow more accurate shooting.

    Flintlock guns have some of the longest lock times, because of the chain of events that lead to the gun's firing: trigger releasing the sear, hammer (known as the cock) falling and creating sparks while opening the frizzen, ignition of priming charge, burning of that charge, and finally the ignition of the main powder charge inside the barrel.

    Although it may seem antiquated since most modern guns do not have locks, the term "lock time" is still used today to quantify the time it takes for a gun to fire after the trigger does its work.]
    Its a long established term
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  6. #21
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    Quote Originally Posted by RichardH View Post
    Its a long established term

    Unfortunately that definition, supplied with out any citation, does nothing to clarify the interval we are discussing.
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    Quote Originally Posted by Turnup View Post
    Unfortunately that definition, supplied with out any citation, does nothing to clarify the interval we are discussing.
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  8. #23
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    I have invented a new word. Whooble-Hoop. The Whooble-Hoop is the time taken from the trigger release to the pellet exiting the barrel in an airgun.

    It does NOT cover cartridge guns, greyhound races or shopping trolleys as they have their own words. It does sound good and make you smile when you say it though.

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    Quote Originally Posted by tinbum View Post
    I have invented a new word. Whooble-Hoop. The Whooble-Hoop is the time taken from the trigger release to the pellet exiting the barrel in an airgun.

    It does NOT cover cartridge guns, greyhound races or shopping trolleys as they have their own words. It does sound good and make you smile when you say it though.

    Tomorrow I will invent a good word about the BSA Lightning, but that may be trickier......
    Quote Originally Posted by Terry D View Post
    I've always preferred to use the term 'shot generation time' when referring to airguns.

    Just saying.
    I think I prefer Terry's choice of words, Tinners!

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  10. #25
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    Weird thread. Lock time means something very specific in the cartridge firearm world. As explained by others above. The time it takes between the trigger breaking and the primer going off. Bolt action rifle where the trigger releases a light powerfully sprung straight-line firing pin, quick. Open-bolt SMG, really slow. For example.

    As far as spring airguns go, you have basically lock time (from trigger break to piston moving), action time (from piston moving until pellet moves - also see start pressure), something that has no generally agreed name describing piston bounce, or not, and then and in some ways in parallel barrel time (how long it takes the pellet, once moving, to get out of the other end). Which is all quite complicated. And that's my attempt to simplify it!

    Pneumatic guns, lock time is the time between trigger releasing the striker and the striker then hitting the valve and releasing the air. Cue start pressure and barrel time. Etc. As above.

    That's all internal ballistics. What happens after is external ballistics and is even more bloody complicated too. Wind and drag and ballistic coefficents and stuff.

    And, frankly, who cares, if you can in practice hit things with the pellet? The differences between different actuon types are tiny, and probably only matter in a real world way if you are are a bench rest guru.

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