Semi Auto Slide Timing Experiment

Semi Auto Slide Timing Experiment

This is a discussion on Semi Auto Slide Timing Experiment within the Reference & "How To" Forum forums, part of the Related Topics category; I've been unable to find anything on this subject (i.e) samples. I've been considering doing some experimental (hi-speed) photography/videography on the entire slide cycle of ...

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Thread: Semi Auto Slide Timing Experiment

  1. #1
    Distinguished Member Array RightsEroding's Avatar
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    Semi Auto Slide Timing Experiment

    I've been unable to find anything on this subject (i.e) samples.

    I've been considering doing some experimental (hi-speed) photography/videography on the entire slide cycle of a semi auto from
    primer strike to battery return. From everything I could read, it appears the entire cycle is VERY critical timing wise.

    The field of view would cover the side of the weapon and a direct look downward into the slide as it advances rearward
    and cycles another cartridge onto the feed ramp prior to closure.

    Reading as much as I can concerning FTF issues, it appears the #1 cause is the magazine.
    Although the camera won't have visual on the magazine itself, it should show timing and/or mis-alignment.

    I also wonder if this would be of use to gunsmiths who deal with this complaint everyday or do they simply "shotgun troubleshoot" the problem? (no pun intended)

    I do understand the timings will be different depending on caliber, slide weight/size etc...

    Might be fun.
    "When those who are governed do too little, those who govern can, and will, do too much." Ronald Reagan

    Do what you can; then do what you must


  2. #2
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    Interesting.

    Personally I believe that many semi-auto handguns are factory "over-sprung" and understandably so I guess.
    Firearm manufacturers need to install a "best compromise" factory recoil spring for all of the ammunition in that given caliber on the shelves and "out there" in the ammunition marketplace.
    So the "factory weight" recoil spring is not always the best weight spring for all brands of ammunition.
    They are a compromise erring on the side of heavy.

    I think that one other thought process by manufacturers is that they want a recoil spring weight/power heavy enough to wallop that top cartridge in the magazine hard enough to send it into the barrel chamber on individual guns that do not feed easily and flawlessly.

    ALSO....double stack magazines that are loaded to capacity contain cartridges that are under an incredible amount of upward tension/pressure....so in order to overcome the metal to metal friction of the top couple of cartridges in the magazine (top cartridge against the feed lips and the underlying cartridge) that gorilla strength recoil spring might be necessary.

    Much will depend on the individual firearm and the smoothness of the magazine feed lip contact surface and the smoothness of the breech face etc etc etc.
    Friction being the enemy of the semi-auto and the manner in which it feeds.

    That having been said most firearms sport a recoil spring that is heavier than it really needs to be. Especially with regard to the single stack magazine semis.

    SO........What exactly ARE the disadvantages of having a gun with a recoil spring that is way excessively heavy for the desired ammunition???

    Often the slide does not stay fully rearward long enough for the magazine spring to position the next cartridge up for a perfect feed. Sometimes with a super heavy recoil spring and a lighter load the slide may not even make it fully to the rear before it starts to head for home.

    And the other disadvantage is greatly increased Muzzle Dip which can radically effect follow up shots because you are waiting for that muzzle to come back up from a greater downward distance.

    It is my personal opinion (and mostly I am talking about the 1911 here) that FIRST the shooter needs to make certain that everything with the gun is correct...AKA
    extractor tension, magazine consistency, an open enough port, throated barrel, etc etc so that it is known that the pistol feeds easily and effortlessly.

    Once THAT is known then the shooter needs to decide what ammunition brand he/she intends to carry and is willing to stay with.

    THEN the shooter can tailor and tune the recoil spring weight to that particular load/ammunition brand or various ammunition brands of a like or similar power factor.

    Amazing things then become possible.

    And they would be Smooth Flawless Feeding, Faster Shot to Shot Recovery, Much Less Muzzle Dip, Less Feeling Of "fighting the handgun" in order to stay on the threat, the "captive feed" of the 1911 allowing the pistol to run perfectly even upside down, easier manual slide operation,

    I think that many folks think that they are "saving" their handgun from frame battering and so opt for an even heavier recoil spring than the factory weight spring.
    When they do that then the slide does not hang to the rear long enough for the mag spring to perform its function and they fight excessive muzzle dip as the slide impacts home with all of that extra unneeded force.

    If shooters are serious about ideal semi-auto firearm performance to the degree that they are willing to be completely consistent with their ammunition and magazine brands then custom tailoring recoil spring weight can provide real life benefits.

    But, if a shooter wants to shoot absolutely everything in one handgun AKA buy and shoot WWB on Sunday and semi-wadcutter target reloads next week and 5 different self-defense ammunition brands and some mags are WILSON and some are cheapo Chinese Import mags and their "extra mags" are different than their "in gun carry mag" and their handgun hesitates on the feed and their extractor is tensioned way too heavy etc. etc. then don't even bother and stay with factory recoil spring weight and suffer with periodic FTF Failure To Feed & Failure To Function.

    OR...if your firearm functions flawlessly with every magazine and light and heavy loads and all bullet types - Great but, you might not know what you are missing with regard to getting on target quicker, better S to S recovery, not fighting muzzle dip, STAYING on target during rapid fire, and an easier firearm to control in general.

    So...bottom line YES, your SLO-MO Videos can prove especially valuable and be incredibly educational for others and especially for your own personal firearms.
    gasmitty likes this.

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    A Good and Serious Thread.

    Folks - This is in How To & Reference.

    Do not junk the thread up with Yuk-Yuk comments.

    They are not very well tolerated in this area of the forum.

    Thanks.

    But, if you have anything relevant, any related thoughts, or anything constructive to add then...please do not hesitate to post.

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    I settle on a carry ammo, then purchase, if available for the model, the Wolff calibration packs. I will then strong hand, weak hand and limp wrist (simulate a weakened state...like being wounded) the weapon until I can find the ideal spring for reliability with my carry ammo.

    I find that double stack mags (another issue than recoil springs) are under sprung usually, single stack over sprung, and most semi auto's over sprung for weak-hand and limp wrist.

    This provides a dichotomy: the right spring weight for the above three scenarios is an undersprung condition for moderate to heavy practice shooting and can cause frame battering. With that said, if your self defense ammo is +p or heavy grain loads, you can use lighter grain and light load practice ammo and it will compensate.

    You should set up your weapons and practice with them like you will fight. I hope for the best, yet plan and practice for the worse and that means weak hand and limp wrist shooting.
    21 years and 21 days, United States Marine Corps & NRA Life Member since 1972

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    One way to tell how compatible your recoil spring is with your carry load is to check out how (and how far) your brass is being ejected.

    If your brass is sailing off into the Stratosphere then your recoil spring weight is very likely on the "too light" side OR you need a fresh recoil spring because the one in your firearm is spent.

    If your ejected brass is barely clearing the port or dropping really close to you...then an under power cartridge, some frame/slide rail grit, or lack of slide/frame rail lubrication is almost going to guarantee a jam because your recoil spring is too heavy.
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    I do not own $100,000 hi speed camera, wish I did as I'm sure a video like this would be far more interesting at 20,000 frames per second.
    This is Gopro video I shot this morning. It was eye opening to me.

    What I learned from my crude video timings:

    1) My Glock 27 Gen 4 from discharge to return to full battery = approx 0.16 seconds. Faster than I can reacquire a target; faster than I can pull the trigger.

    2) Muzzle flip is far more than I thought when looking at in in slo-mo. (Granted; I was poorly mounted using hand held on a wood bench)

    SCXDm9 and NickBurkhardt like this.
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    Actually trouble shooting a firearm is pretty simple once you break down the cycle of operation and know what parts are involved in a specific operation. It is not as much guess work as one would imagine. The cycle is fire, extract, eject, load and fire etc......
    My rifle and pistol are tools, I am the weapon.

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    Quote Originally Posted by 40Bob View Post
    Actually trouble shooting a firearm is pretty simple once you break down the cycle of operation and know what parts are involved in a specific operation. It is not as much guess work as one would imagine. The cycle is fire, extract, eject, load and fire etc......
    Agreed.

    However, (and I am not a gunsmith), I see "subsets" or nuances of the (4) primary movements you mention.
    (i.e)..Prior to EXTRACT is slide movement rearward. Incomplete or partial rearward movement could be light cartridge load, recoil spring too strong (I ran into this when I tried a non Glock spring)...improper slide oil for cold weather ops.

    I see a host of problems when diagnosing FTF issues, though most seem to fall into primary groupings..some easy to spot; some not so easy.
    "When those who are governed do too little, those who govern can, and will, do too much." Ronald Reagan

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    Here is some good slowmo. Unfortunately they are shot with the gun underwater.

    ... evil will always triumph because good is dumb! - Dark Helmet

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    Go to the 5 minute mark to start seeing what you are looking for.
    Bad Bob likes this.
    ... evil will always triumph because good is dumb! - Dark Helmet

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    Shockingly violent!

    Quote Originally Posted by RightsEroding View Post
    I do not own $100,000 hi speed camera, wish I did as I'm sure a video like this would be far more interesting at 20,000 frames per second.
    This is Gopro video I shot this morning. It was eye opening to me.

    What I learned from my crude video timings:

    1) My Glock 27 Gen 4 from discharge to return to full battery = approx 0.16 seconds. Faster than I can reacquire a target; faster than I can pull the trigger.

    2) Muzzle flip is far more than I thought when looking at in in slo-mo. (Granted; I was poorly mounted using hand held on a wood bench)

    Things gun forums have taught me:
    -Some people shoot guns other "run" them.
    -I don't dislike Glocks but often dislike Glock owners.
    -Open carry is to a handgun as bluetooth is to a cell phone!
    -Simple math can deliver posts per day... some gun forum members need to get out more!!!

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    QK, you make me feel like I just sat through a 10th-grade chemistry class. My mind is all used up for the day.
    QKShooter likes this.
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    Quote Originally Posted by SCXDm9 View Post
    Shockingly violent!
    That's what I thought. I attribute some of that to my very low position behind the shooting bench; maybe.

    I think next time I'm going to analyze (time) how long it takes me to reacquire the target (with) accuracy.
    A shot timer can do this but I prefer looking at a frame by frame for timings.
    "When those who are governed do too little, those who govern can, and will, do too much." Ronald Reagan

    Do what you can; then do what you must

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    Way back I used to shoot competitively, both IPSC and steel challenges. VERY different loads for both. IPSC major power factor required my 200 gr. bullets running about 875 fps, while with the steel as long as they didn't take too long getting to the target all was well... i just wanted as little recoil as possible. My records show for IPSC, about 870 fps with 5.9 grains of W-231 while the steel loads meandered along at about 585 fps over 4.4 grains.

    Obviously, way different slide momentum being imparted by those two loads. Given equivalent slide mass, the only way to manage slide velocity was to adjust the recoil spring. I was running, IIRC, 18 pound springs for IPSC and switching to either 11 or 7 pounders (can't remember) for the steel.

    So, bottom line, yeah, spring weight is crucial to proper slide velocity, which in turn is critical to proper functioning. Too little momentum and the slide won't go back far enough to pick up a new round. Too much and it moves so fast the new round can't come up far enough.
    =
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  15. #15
    TRX
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    I posted this over in the amtguns.info forum a while back. It's about the Auto Mag, but it's relevant to automatics in general.

    cocking piece interchange?! - AMT Guns forum - Page 2

    <snip>

    If I remember Kent Lomont's article correctly, the extra bolt weight improved feed reliability.

    [anyone who knows better, feel free to jump in here!]

    When you pull the trigger, the upper slides back about 5/16 of an inch. The bolt rotation pin (or stub pins) twist the bolt to unlock it, and the bolt, firing pin, cocking piece, recoil rods, and front ends of the springs continue moving back. Normally if only one end of a spring moves, you figure the "spring weight" as 1/2 of the total weight.

    Call this the "recoil assembly", for lack of a better term. The initial 5/16" "kick" has to provide enough energy for the flying recoil assembly to overcome the friction of the bottom of the bolt against the top cartridge in a full magazine, plus cock the hammer, plus overcome the recoil springs. There's a lower limit on the strength of the recoil springs; they have to have enough oomph to pull the recoil assembly forward to strip a cartridge off a full magazine, push the entire upper assembly forward, and turn the bolt into battery. Oh, and they can't be too stiff for someone to cycle the action.

    Again according to Kent Lomont, with the right ammunition and lubrication, an 8" or 10" barrel Auto Mag can do without an accelerator. But cold weather, ineffective lubricant, or weak ammunition can cause short-stroking or jams, so the accelerator was added to kick recoil assembly back hard enough to do the job.

    You only have so much initial kick, and the recoil springs can only be so weak, and the magazine spring has a lower limit as well, or it can't pop the #2 cartridge up fast enough after the first cartridge has been fired. The hammer spring has to have enough oomph to fire the primer.

    You can add more kick by playing with the accelerator rate, but if you add too much you'll start beating up the bolt rotation pin, plus the bolt will bounce back faster, which can cause feed problems. Adding a bit more weight will work just as well, without the "bounce-back" and feed problems being as bad. Filling in the bolt track is about the only way to add much weight.

    On a normal gun you'd load up a few magazines full of correct ammunition (SAAMI or military spec), and if it didn't cycle cleanly, you'd know the problem was with the gun. For example, if a 1911 fails to operate properly with US Army hardball .45 ACP, the gun is defective, no matter who made it or smithed on it.

    There was never a SAAMI spec for .44 AMP, and commercially loaded ammunition apparently exceeds the range of pressure that the Auto Mag will reliably function with. Since most owners don't reload, they sometimes wind up with pistols that won't function reliably with whatever ammunition they have.

    The changes in the recoil springs, solid bolt, etc. were attempts to get the Auto Mag to function across a wider range of ammunition power and operating conditions (lubrication and cold weather, basically). For some reason customers were unhappy if their expensive stainless steel hand cannon didn't reliably digest Pancho's El Cheapo Reloads as well as Super Vel or Norma.

    There's nothing *wrong* with the Auto Mag design, it's just that the "energy budget" for operating the works has a fairly narrow window, and if the ammunition isn't within that window, problems can crop up.

    </snip>
    QKShooter likes this.

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