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locking block size variation, lug to block clearance, impact on accuracy.....

Discussion in 'GSSF' started by Rusty Phillips, Nov 20, 2002.

  1. Rusty Phillips

    Rusty Phillips Moderator Millennium Member

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    i have been wondering about this for a while now and wasnt really sure how to phrase the question





    ok

    100 % STOCK GLOCKS (for gssf amateur, or stockmeister, or?)

    i take my 24 frame and 24 slide

    i press on barrel (above the chamber - the hood?)

    i do not see very much movement




    i take my 17 frame and 17 slide (and for that matter my 34 frame and slide as well)

    i press on barrel

    the barrel starts to drop down and the slide moves slightly backwards

    when you fit a fitted barrel - this is what you are trying to minimize - right?




    i took my 17 frame (std connector) and my 24 frame (-connector) out to the range today with the 17 slide and shot the same slide on both frames

    in my unscientific (sp?) test.... the 24 frame (and lighter connector) showed a visibly smaller group than the 17 frame

    well duh?!?! it had the lighter connector....



    if i had more time today i was going to change the connector out, but i didnt, so i didnt....



    has anyone looked at two identical glocks where one clearly is more accurate than the other and observed a variation in any of the component sizes/dimensions ?

    1. the distance between the trigger pin hole and the top of the locking block cam surface might be greater

    2. the hole in the frame for the trigger pin might be higher relative to the slide rails (and the rest of the frame)?

    3. the slide rails on the frame might be slightly lower relative to the hole for the trigger pin (and locking block - and the rest of the frame)?

    im going to try to get my old g19 back (from who i sold it to) and shoot it side by side with my g17.... i swear that 19 was a tackdriver, and this 17 shoots patterns, not groups

    anyone have a huge stash of used g17 locking blocks that i can sort thru to find the oversized ones (holes drilled lower relative to the top of the block)?

    does anybody make or has anyone made a "fitted locking block"?
     
  2. TJC

    TJC "No Compromise" Millennium Member

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    Rusty,

    You really have TOO MUCH time on your hands. ;e
     

  3. DEJ/FL

    DEJ/FL Millennium Member

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    Rusty
    Have you given any though to the "Jerk" behind the trigger causing your G17 to "pattern" instead of grouping????
    Dan:cool:
     
  4. Rusty Phillips

    Rusty Phillips Moderator Millennium Member

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    too much time? maybe too much time spent in my car going from one place to the next

    spent the last two nights in a hotel, today i drove 300 miles
    (stopping at two mills) and finally made it home, hopefully tomorrow will be a short day 90 miles out, do my thing, and then 90 back

    not enough time spent at home




    at any rate - back to this mixing and matching of parts....

    next time i get a chance im gonna try all three of my frames (g17 frame/std connector, g24 frame/-connector, and g34 frame/-connector) with the g17 slide to see if there is a difference with me shooting them, to see which is most accurate for me

    if i can i might also finally get a -connector on the 17 frame..... i havent up to now because most of the time i have been shooting the 17 slide with the 34 lower (i had never considered putting the slide on the 24 lower up until now)

    im also going to try to talk one of the better shooters at mid carolina rifle club into shooting all three to see what he gets.... if he shoots all three equally well then i know once and for all that that nut behind the trigger is loose and needs to be tightened

    later
     
  5. DEJ/FL

    DEJ/FL Millennium Member

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    im also going to try to talk one of the better shooters at mid carolina rifle club into shooting all three to see what he gets.... if he shoots all three equally well then i know once and for all that that nut behind the trigger is loose and needs to be tightened

    later [/B][/QUOTE]


    NUT?????LOOSE?????????
    You MUST be talking about the JERK behind the trigger;Q ;f
    Dan:cool:
     
  6. Rusty Phillips

    Rusty Phillips Moderator Millennium Member

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    ok - now im really going out into deep water

    i tear apart all three guns

    the 17 block has a number 6 cast into it

    the 24 block has a 2 cast into it (surrounded by a square) - of course it has the 2 holes for both pins

    the 34 block has a 2 cast into it with no square

    id post pics, but i dont have my digital camera with me, so i cant

    im sure this is in the glock armorers book - right? what do the numeric codes stand for?

    i tried searching with no success

    my curiousity piqued - i take out the block on my 26 - it has a number 11 on it
     
  7. Don At PC

    Don At PC Senior Member Millennium Member

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    Rusty;

    You have definately been on the road much too long.;Q ;Q ;Q
     
  8. DannyR

    DannyR Moderator Millennium Member

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    Rusty,

    You need to get home, kiss the baby and hug the wife.
     
  9. 21 shooter

    21 shooter

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    The results may be boring, or quite interesting. Let us know how it turns out.
     
  10. Rusty Phillips

    Rusty Phillips Moderator Millennium Member

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    spent an hour at the range today (shooters choice in columbia sc) with three lowers (17,24,34), my g17 slide, and my 17 and the 34 barrel

    i shot the 17 and the 24 frame with both the #2 stamped block and the #6 stamped block (the 34 frame was the #2 block only)

    it sure seems that the 24 frame - regardless of which block was in it, was more accurate than the 17 or 34 frame

    in the 24 lower, the #2 block gave a (i only shot one 10 rd group) better looking group than the #6 block

    how much of it was me, and how much was the gun..... well....

    im going to keep playing with various parts combinations..... but i really need to get one of the hotshots at mcrc to shoot the combinations...... to eliminate me as a variable

    and id like to try this on a ransom rest..... but not likely to happen anytime soon

    i also shot the 24 lower, 17 slide, and both the 17 and 34 barrels.... curiously the 17 barrel was much more accurate

    again this was just a quick and dirty evaluation
     
  11. mcginnes

    mcginnes Safety Officer Millennium Member

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    First, ask yourself if playing with frames and uppers is going to improve your accuracy more than practicing. No? Knock it off and go practice. If yes, it's time to get Scientific.

    Test one thing at at time. First, is the 24 frame more accurate than the 17 frame.
    <h4>Materials</h4>
    1 Glock 17 lower.
    1 Glock 24 lower.
    (it would be better if both lowers have the same type of connector).
    1 Glock 17 upper.
    200 rounds of ammo, all from the same lot.
    20 bullseye type targets.
    1 shooter.
    1 assistant.
    1 quarter.
    <h4>Method</h4>
    The assistant will flip the quarter, and give the shooter the appropriate frame. The shooter should not know which frame they are using.
    If its heads, use the 17 lower first, and fire 10 rounds at 25 yards at a fresh bullseye target, (preferably from a rest*). Then fire 10 rounds using the 24 lower on a fresh target. If it is tails, switch the order. The shooter should measure the maximum spread of the groups, center to center (Group size). The assistant should record the group size in inches for each lower side by side as pairs (and below any previous measurements). For example:

    Code:
    pair | 17lower | 24lower
    1    | 4.3     | 3.5
    2    | 4.0     | 3.9
    etc.
    
    repeat 10 times.
    Compare the group size for each pair. If the 24 lower produces a larger group 2 or fewer times, then you have evidence that the 24 lower groups better.
    If not, you can
    1. "fail to reject the null hypothesis that there is no difference in the two lowers" and get on with your life.
    2. shoot another 10 pairs. This time the 24 lower can produce 4 or fewer groups that are larger over the 20 pairs.**
    3. Post all the data, and I can do some more involved analysis.
    <h4>Disscussion</h4>
    Personally, I'd go practice more, but I'd like to see the results. If there is a difference between the lowers, then you can start looking at different parts. Since you are only testing one pair of frames, the results are only going to apply to this one pair of frames.

    You are flipping the quarter for each of the 10 pairs. You are doing this to eliminate shooting order as a variable. If you always shot the 17 lower first, you wouldn't be able to tell if you shoot the 24 lower better, or if you just shoot your second group of 10 shots better. This also keeps you from guessing which frame you are shooting, or otherwise biasing the test.

    The shooter shouldn't know which frame they are using to keep from "fudging" the test. If you think the 24 frame shoots better, then you might subconciously work a little harder to get a good group with that frame. The shooter is measuring the groups for the same reason. Since the shooter doesn't know which frame is which, the assistant has to record the data to put it in the right spot.

    * Firing from a rest will test whether one frame is more accurate, but will mask differences in the triggers. Firing free hand is go to test whether You shoot one frame better than the other, including trigger differences. But, it's probably going to increase the variance in group size, and make it harder to tell if one frame is actually better.

    **This is a no-no that might get you a nasty letter in a scientific journal, but I think we can get away with it here.
     
  12. Fireglock

    Fireglock Which is worse?

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    Don't you just love it when mcginnes talks scientific? ;f
     
  13. DEJ/FL

    DEJ/FL Millennium Member

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    Sounds like to me that after all this testing.........It's still boils down to the "JERK" behind the trigger;e ;Q
    Dan:cool:
     
  14. mcginnes

    mcginnes Safety Officer Millennium Member

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    We can test that... Sorry, I've been spending a lot of time with the thesis lately.

    I agree though, it's more likely the Rusty trigger nut.
     
  15. DannyR

    DannyR Moderator Millennium Member

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    LMAO;f

    Thanks, Guys, I needed that.:cool:
     
  16. Don At PC

    Don At PC Senior Member Millennium Member

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    And I thought I had too much time on my hands. ;Q ;Q ;Q ;c ;c
     
  17. mcginnes

    mcginnes Safety Officer Millennium Member

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    ;u ;u ;u ;u
    LMAO too.
    If I worked this hard on my thesis, I'd be done by now.
     
  18. Fireglock

    Fireglock Which is worse?

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    You mean we're not being serious? :)
     
  19. DEJ/FL

    DEJ/FL Millennium Member

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    ;f ;a ;f
    Dan:cool:
     
  20. 21 shooter

    21 shooter

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    Having read the mcginnes scientific method proposed to evaluate the question put forth by Rusty, I have come to the conclusion that trading the pistol for one that shoots better is much easier. It also does not give me a headache. ;f