POA/POI affected by recoil spring?

Discussion in 'General Handgun Discussion' started by Poink88, Jul 25, 2011.

  1. Poink88

    Poink88 New Member

    1,116
    0
    0
    If your semi-auto pistol is using an 18# recoil spring and you replace it with a 13# spring. Will it change your POA/POI? If yes, should you expect it to go higher or lower (if using same ammo)?
     
  2. IGETEVEN

    IGETEVEN New Member

    8,358
    4
    0
    That can only be determined once the first few shots are fired and the caliber type, weight of original handgun and the ammo grain used. Adjustments for POA/POI may, or may not be needed.
     

  3. JonM

    JonM Moderator

    20,110
    19
    38
    It wont affect it. Newton still applies. The gun wont move or recoil until the bullet exits the muzzle. The force of the round going forward is equal to the rearward force until the equation changes as the bullet exits. The forward thrust is no longer there to offset the rearward force or recoil. So this makes weight of spring a moot issue in terms of affecting poapoi

    You can see it in action on any highspeed camera shot of a gun going off
     
  4. Poink88

    Poink88 New Member

    1,116
    0
    0
    Hmmm. I agree that Newton's law applies but for me, it starts at primer ignition not when the bullet exits the barrel. As the bullet moves forward, the slide moves backward simultaneously.

    The reason heavier bullets hit higher than lighter bullets (early part of trajectory) is because they stay in the barrel longer (travels slower).
     
  5. JonM

    JonM Moderator

    20,110
    19
    38
    Yes but the force forward still equals rear. Equal and opposite. Recoil doesnt start till the bullet is gone. Weight of bullet and external ballistics is different than internal ballistics. Same exact bullet charge primer etc with only a spring change poapoi wont change.
     
  6. Poink88

    Poink88 New Member

    1,116
    0
    0
    The force is equal but will the speed of the slide recoil not change with a lighter spring? Thus, won't it affect how fast the barrel tilts upward as well as the pistol itself?
     
  7. JonM

    JonM Moderator

    20,110
    19
    38
    yes but that has no effect on poa/poi of the bullet itself. the spring and slide dont start moving until after the bullet is gone. this is true of revolvers too.

    this demonstrates it the best. the flash is when the bullet has left the barrel and recoil starts.

    [ame=http://youtu.be/s5pVya7eask?t=23s]‪high-speed video of scope and barrel flexing on a 50BMG‬‏ - YouTube[/ame]
     
  8. Poink88

    Poink88 New Member

    1,116
    0
    0
    Jon, I would respectfully disagree.

    The slide and spring definitely will not move as fast as the bullet but I believe they start moving as soon as you had an ignition. Again, this is the reason why heavier (slower) bullets tend to hit higher than lighter (faster) bullet. As fast as they fly out, they are still affected by the barrel movement/recoil.

    Of course the entire pistol also start the recoil process at the same time and depending on the grip, POI may also change.

    Just my personal beliefs/understanding which may be wrong.
     
  9. Poink88

    Poink88 New Member

    1,116
    0
    0
    Much as I wanted a more definitive answer, I guess this is the simplest way to go through this. Thanks!
     
  10. IGETEVEN

    IGETEVEN New Member

    8,358
    4
    0
    Ya just gotta go with the flow man. Life always requires them little adjustments to maintain one's overall personal proficiency. ;)
     
  11. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

    11,380
    2
    0
    This is a good question, but easily rectified. In a locked breach semi-auto pistol, the slide/barrel are as one until the barrel tilts/drops/rotates to unlock from the slide. Think of this; The bullet is pulling the barrel forward during firing while the recoil is pushing the slide back. These two forces are equal until the bullet leaves the barrel. Then and only then can the barrel/slide begin the sequence of movement that will allow unlocking.

    This is why such pistols are not very ammo sensitive. They work with a wide variety of bullet weights and velocities. They do not have to be "tuned" to one specific load.

    Of course an unlocked breach pistol like a High Point or most guns in .25, .32, .380 use simple mass of slide and recoil spring tension to retard the slide movement for a time so pressures "should" be lower upon opening.
     
  12. Poink88

    Poink88 New Member

    1,116
    0
    0
    Robo...thanks a lot! That helps me understand the process a lot more now. I thought the slide moves backwards right away. So the initial upward movement is recoil to the entire pistol and doesn't include barrel tilt (that you get when the slide cycles).

    This ties in with IGETEVEN and JonM's response very well also. Thanks guys!