Failure to extract - Causes and Cures

Discussion in 'PF-9' started by Silverbullet, Dec 15, 2011.

  1. Silverbullet

    Silverbullet Active Member

    122
    Oct 15, 2011
    Tulsa, OK
    Just thought we might we might get the combined mental horsepower of KTOG working on this. Surfing other forums, I found the following quote:

    "A light powder load, a stiffness in the movement of the slide, a really dirty chamber, or a too heavy slide spring can all look like a failure to extract, with the expended casing not getting out of the chamber. "Limp Wristing", not maintaining a firm grip on the pistol, can also cause failures to eject. A worn or binding extractor is more likely to cause a failure to eject, rather than a failure to extract, in most cases."

    Note: We most often are talking about failure to EXTRACT, not to eject
    We focus mostly on the extractor
    We seldom talk about the recoil spring as a possible problem

    There was a recent post on this forum where the gun had NO extractor and it still functioned most of the time! One thing I would like to see discussed is possible timing issues. As I understand it, the bullet is out of the barrel before extraction begins. If sooner, pressure in the case would bind the cartridge in the barrel.
    I look forward to your replys:)
     
  2. haugrdr

    haugrdr Well-Known Member Supporter

    Jan 4, 2008
    Daytona Beach
    Limpwristing can cause failure to extract also.
     

  3. RobzKT

    RobzKT Well-Known Member

    Jan 31, 2010
    Texas
    Yes... an overly strong set of recoil springs could mess up the slide's timing. Stronger isn't always better.

    The expansion of Off-Brand ammo can cause expansion issues that trnsfer to extraction problems. Although some think the PF-9 SHOULD eat any brand the owner feeds it, Many won't. One MUST rule out ammo as being a factor.

    So far...
    Extractor
    Recoil Springs
    Limpwristing
    Ammo expansion/selectivity

    Next on the list???
     
  4. Hasdrubal

    Hasdrubal Member

    50
    Sep 11, 2011
    Puyallup WA
    Without being able to measure the strength of several recoil springs it's hard to be sure, but it seems like that would be a problem if there were aftermarket springs available- as far as I know, KT makes the only recoil springs for this gun. With coil springs, I don't see there being enough variety, unless the factory has the wrong spec to start.

    Maybe someone else knows this better than I do, but wouldn't timing be determined by the shape of the barrel lug? The part where the takedown pin rides, if it were shaped shallower or steeper? The slide speed could be changed by the powder charge or the spring strength, but I think the relative positions of the barrel and slide are pretty much fixed.

    I've seen more than a few threads where the user found that FTE problems went away after tightening their extractor retention screw, and many where a new extractor kit from KT fixed the problem. Several more where the problem went away and then came back.

    I would like to see a stronger spring from KT, or a switch to a pivoting extractor with a coil spring. I believe coil springs are likely to be sourced from a larger supplier than an oddly shaped leaf spring, and therefore less prone to a bad heat treating and loss of spring tension.

    My FTE problems occurred with several brands of factory ammo as well as reloads that function fine in several other brands of pistol.
     
  5. PF9Newbie

    PF9Newbie New Member

    Nov 22, 2008
    Wisconsin
    Another cause of failure to extract/eject, although perhaps counter-intuitive, is a bad magazine/weak mag spring. This is so because a weak mag spring can allow a roiund to "release" from the mag early as the bolt is extracting the fired case. Then, as the front of the new cartridge rises, it can strike against the extracted case, preventing the case from ejecting and instead, the case is then re-chambered, with the new cartridge then jamming against the re-chambered, fired case.

    This phenomena/problem is not, of course, limited to the PF-9, as I have, in the past, had problems even with my 1911s with bad/poor mags. The solution with the 1911s is always to use quality made mags, and I have gone through many in testing over the years to isolate and get rid of bad mags. With both of my 1911s, in fact, the only times I ever experienced any feed or extraction issues was with poor mags.

    Thus, in my opinion, many of the various problems experienced with the PF-9 are due to poor quality magazines, which I think are the weakest link in the PF-9. Wish Wolff would start making mag springs for the PF-9. I think it would solve a lot of issues.

    Jim R
     
  6. hmecker

    hmecker New Member

    21
    Mar 23, 2011
    Timing may very well be a problem. First one of my pf9 FTEs were corrected by cutting a half coil at a time of the recoil spring**posted by another poster** to reduce tension...almost 2 full coils.
     
  7. partsguy22

    partsguy22 New Member

    90
    Apr 27, 2011
    DFW
    I wonder if Keltec over sprung the PF-9. I was in Wolff springs site and saw they offered spring packages for the 3AT and Ruger clone but the recoil springs for the 3AT was listed as 11lb and the LCP was 9lb thats a 22% difference . I wonder how the LC9 and Pf9 compare?
     
  8. PF9Newbie

    PF9Newbie New Member

    Nov 22, 2008
    Wisconsin
    The LC9 slide is several ounces heavier than the slide of the PF-9. So it has greater inertia and does not need quite as heavy a recoil spring as the PF-9 in order to achieve the proper timing in the LC-9. There are probably some differences in rails, etc, affecting the friction coefficient which also contributes to differences in recoil spring strength requirements.

    Jim R
     
  9. Buddy

    Buddy Member

    272
    Nov 5, 2011
    Not sure if it was a couincidence or not but after I took my extracter spring and bent it so it looked like a peak of a house my extraction problems went away. I think it also acted like a lock washer because of all the extra tension it placed on the screw.
     
    Last edited: Dec 16, 2011
  10. Jamie

    Jamie Well-Known Member

    Dec 14, 2010
    Thinking about this a bit, it would seem a stronger spring would resist the initial movement of the slide giving the fired case time to contract away from the chamber making extraction easier. Too heavy a spring though might cause 'stovepipes' since it wouldn't allow the slide to move all the way back.
     
  11. PF9Newbie

    PF9Newbie New Member

    Nov 22, 2008
    Wisconsin
    That is essentially correct. The slide has to stay closed, with barrel locked in battery until the pressure subsides to safe levels, and to give time for the case to contract a little, allowing for extraction. Too weak a recoil spring would allow the slide to start moving back too soon. In an extreme case, this could lead to case rupture if the pressure was still high, or the case might not have contracted, making extraction difficult or causing extractor to slip off the rim. This is why the recoil spring needs to be replaced every 1000-1500 rounds, as it wears/weakens.

    On the other hand, as you note, too heavy a spring would delay the action opening to the point the pressure falls too low to properly activate the slide movement, possibly resulting again in ejection problems as the slide might not be moving fast enough. And the slide might not then move far enough back, or may move forward too fast, causing feed problems, as the magazine spring cannot then move the next cartridge into line fast enough.

    So timing has to rely on a careful balance of recoil spring tension and magazine spring tension in order for the gun to function properly. Undue friction, such as improperly greased rails, etc can upset that balance as well.

    Jim R
     
  12. Ape

    Ape New Member

    Jul 16, 2008
    Colorado