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bullet seated deeper after cycling

Discussion in 'Band of Glockers' started by jundeleon, Mar 3, 2007.

  1. jundeleon

    jundeleon

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    I have asked this before but cant seem to find the old thread.

    Whenever I cycle a round in and out of my para p14, the bullet comes out pressed or seated deeper into the case.

    Ive tried this both on local ammo and imported rounds. the result is the same, overall length of the cycled round shrinks.

    It happens with just one cycling.

    Whats wrong with the gun?

    Is it safe to fire the ammo if the bullet is seated deeper than usual?
     
  2. horge

    horge -=-=-=-=- Lifetime Member

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    Hi!

    Bullet setback is a reality, especially in pistols with
    steep ramps (as in most locking breech designs --less so
    for most fixed-barrel blowbacks), and particularly with
    non-factory ammo, which isn't crimped as stoutly.

    Most US factory ammo is rated for only two (2) chamberings
    and unfired extractions.

    Bullet setback increases case pressure when the cartridge
    is finally fired, with potentially disastrous results for
    high-pressure cartridges like, say, .40 S&W, for which a
    setback of merely 1/10 of an inch can DOUBLE the resultant
    case pressure.... so be very careful.

    You shouldn't get setback in factory ammo after just one
    chambering. Either those are actually reloads, or your ramp
    could use some polishing. There is also some data to suggest
    that dimpled (or pimpled) followers help minimize unproductively
    (and unnecessarily) hard contact between the bullet and the ramp.

    hth.

    horge
     

  3. jundeleon

    jundeleon

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    Could the "stiffness" of the recoil spring also contribute to bullet seating?

    And, how do I polish the ramp?
     
  4. dv8

    dv8

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    Hmmm, first I've heard of that. Quality ammo (and a pistol thats working right) shouldnt cause setback.
     
  5. isuzu

    isuzu

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    Setback happens when you chamber ammo. Some may not be noticeable to the eye. Even the M16 ammo suffers from this. What I've noticed was when you hesitate to let go of the slide when you chamber ammo, setback is more noticeable.
     
  6. horge

    horge -=-=-=-=- Lifetime Member

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    dv8,
    As isuzu points out, setback is a mechanical inevitability. As for
    the "two chamberings" issue, it's basically legalese, if I understood
    Dean Speir (!!) correctly: SAAMI case pressure ratings are guaranteed
    only for two cyclings of an UNFIRED cartridge. A proper factory crimp
    might resist a lot more and still keep pressure increases to within
    SAAMI spec, but what the lawyers and bean counters are willing to
    guarantee may be another matter.


    Jun,
    Make sure the ramp NEEDS polishing. Ocular examination, sabay na
    hipuan mo rin with a dry finger, and you'll know if the ramp
    is anywhere near mirror-smooth.

    I have an Armscor Practical 1911 that came with a ramp that was
    satin-hardchromed (along with the rest of the frame), and thereby
    producing inordinate friction with bullets during chambering.

    I just placed some utlrafine steel wool --which is reminiscent
    of cotton candy in texture-- between a finger (the one closest
    in radius to the ramp curve) and the ramp, and lightly rubbed
    the ramp over time, to a more reflective sheen. Now it chambers
    slicker than snot on a doorknob.

    You don't want to alter the ramp contour, but merely to smoothen out
    tiny irregularities in the ramp's surface texture. Making sure the pistol is
    bone-dry beforehand will help in cleaning up the inevitable buildup of
    stray, broken steel fibres, with a magnet.

    If you don't have any ultrafine steel wool, and don't mind travel
    to PBDionisio firing range, let me know (PM). I still have a
    small bag of the stuff, and can leave a roll (see below) for you
    with Cute or maybe with Ianne. Heck, maybe I can mail you some.

    [​IMG]

    What strength recoil spring are you using, anyway?
    An overly robust spring can not only encourage setback, but
    batter the hell out of your slide, etc...


    horge
     
  7. jundeleon

    jundeleon

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    horge

    Would it be better or easier to get the job done if I use a dremel tool and some polishing compound on the ramp?
     
  8. horge

    horge -=-=-=-=- Lifetime Member

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    IMO lang, ha? But...

    DO NOT under any circumstances use a dremel and compound
    to polish the ramp + chamber lip. Use of those dread weapons is
    best left to truly qualified gunsmiths, as you run the risk of
    taking away too much metal, altering the slope and contour of the
    ramp, which in turn can destroy reliable cycling and chambering
    function in the pistol.

    Leave the destructive-DIY-dremelling to McOliver, okay? :supergrin:
    ParaOrd kasi... if it was a cheaper Armscor, it could merely be an
    interesting learning experience.

    Just ten minutes of light rubbing with ultrafine steel wool can
    smooth out a lot of any roughness to the finish of the ramp,
    and help ease chambering (and therefore reduce the force imparted
    to the bullet's nose as it goes up and in).

    While a mirror polish is desirable, just enough smoothing to
    promote easy chambering and to eliminate severe bullet setback
    is our objective. Using a design-spec recoil spring wouldn't hurt
    either. Nor would sticking to factory roundnose for ammo.

    Good luck!
    :)

    horge
     
  9. jundeleon

    jundeleon

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    thanks horge

    btw i am still using the stock recoil spring.

    still too stiff as i have less than 500 rounds on this gun.
     
  10. Blitzer

    Blitzer Cool Cat

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    I have used a Dremel tool, a felt bobbin about 3/8" in diameter and Flitz metal polish without any dreaded results. It will shine the ramp to a mirror brightness without removing any measurable amount of the metal. Just don't polish the chamber as it should be correct from the factory.

    Cheers. :thumbsup: :supergrin: ;)
     
  11. horge

    horge -=-=-=-=- Lifetime Member

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    Thanks for the input, Blitzer!
    :thumbsup:

    You're right, I had read too much into jun's 'Dremel' comment,
    imagining the use of stones. In the Philippines, GLO and MC
    metal polish are the near-equivalents of old Flitz.
     
  12. dv8

    dv8

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    I did a search on Dean Speir and bullet setback and can only find some article regarding a glock 22 that KB'd where the suspect was a .40 round. The round had been loaded and unloaded for approximately 45 times within a 30 day period. But they really couldnt say conclusively.

    On the other hand, your comment about commercial ammo being rated for only 2 rechamberings got me thinking. So I decided to do a quick test on 3 guns, an HK expert, P-14 and a 1911 parts gun I built on a Caspian frame. Both 1911s use a Para barrel (integral feedramp). The P-14 has somewhere around 10k rounds through it, parts gun around 5k and the HK 3k. All are 45acp. All have been 100% reliable and have been fed ball, swc and flat points over the years. With the exception of the HK, the 1911s have used mostly hard cast lead bullets. The 1911s have a proper throat job and feedramps polished to a mirror finish. Chambers clean with pistols properly lubed.

    Ammo used was 1 of each, regular Winchester 230grn ball, Federal 230grn jacketed hollow point and my cheapo reloads using Speer 200grn FMJ bullets loaded on a Lee reloader with Lee dies. I chambered each round 6 times, twice using the slingshot method (pull slide back, let go), twice using slide release and twice riding the slide forward to the point where I needed to push the slide a little to get it to close. I measured each round using a digital caliper before and after chambering. End result no change in OAL (overall length).

    What does this prove? Not much, just the fact that a few rechamberings on my pistols with my ammo didnt cause any setback. Will there be setback over time? Maybe, because no two pistols are alike. Maybe it will happen with a few more tries but I'm too lazy to do anymore right now and I dont make a habit of re-chambering my carry loads over and over. Then you have the different ammo types and manufacturing processes....

    As for whats happening on the original posters pistol, its hard to say but I agree that he needs to check the feedramp first. I polished my feedramps, the top bevel and under the barrel hood. I also did a little throating job on them. Its one of the first things you do to a 1911 to ensure reliable feeding. But if you're not sure how this is done, its best left to a professional. Its real easy to ruin a barrel if you dont know what you're doing.
     
  13. mc_oliver

    mc_oliver

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    HEY!!!...ay teka mod ka pala. :supergrin: :tongueout:
     
  14. horge

    horge -=-=-=-=- Lifetime Member

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    Bosing Oliver,
    Hah! You're the uber-Mod.
    ...Modifier of pistols, that is.
    :tongueout:
    :supergrin:


    dv8,
    That's a lot of quick testing :)
    I'll ask you to recall what I posted in my first response to you:
    Unless a manufacturer can guarantee 100% Quality Control on all ammo
    it puts out, the bean counters and lawyers in its employ are always going
    to hedge manufacturer's guarantees.

    I'm glad you Googled the Dean Speir ".40 kB-notes" webpage, because
    it essentially indicates the same (w/ respect to .40S&W). Here's a snapshot
    of the page's text:

    from http://www.thegunzone.com/glock/kb-notes.html
    ...[​IMG]


    IIRC, cycling-hedged guarantees are also applied to many batch-sold
    9mm, .22 LR and other cartridge calibers/brands. It is likely not as
    much of an issue for low-pressure cartridges like the .45 ACP and
    10mm "Lite", but then jundeleon must have had reasons for not specifying
    his pistol's chambering, despite my oblique fishing.

    horge
     
  15. dv8

    dv8

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    Yeah, that rated for 2 rounds comment really bothered me so I had to see for myself. Thanks for dropping that Speir guys name, he's got some interesting stuff to say and makes for some good reading. Makes me glad I'm a 1911 and 45 acp guy (Beg your pardon Glockers! :)) I will admit though that I used to have a 26 but sold it to finance a shotgun (I like the bigger bang).

    Anyway, I hope you get your problems solved jundeleon. Based on you're sig line you're still well protected until you do.
     
  16. jundeleon

    jundeleon

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    horge,

    its 45 acp
     
  17. mc_oliver

    mc_oliver

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    HEH! :supergrin:

    *******

    I just skimmed through all the responses so I'm not sure if it's been covered. Here are some more things to check:

    1. Mags. Is it happening on all mags?

    2. If Yes, check the mag catch. It maybe holding the mags much lower than it's suppose to be causing the bullet to hit the lower part of the ramp.

    3. If No, tweak the lips on that offending mag.

    4. Check the upper chamber inside hood for any burrs or sharp edges that the bullet might catch on.

    HTH.
     
  18. Allegra

    Allegra

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    haba ng thread :)
    the gun was a p14 , di ba para barrels have integrated ramps?
    Nothings wrong w/ it tingin ko
    What ammo was used?
    Most metal jacketed rounds are pushed into the case lalo pag malakas ang spring
    My beretta used to do this w/ sliver tips and fmj
    Maybe it will , maybe it wont
    It's prudent to inspect any ammo that has been chambered kahit once lang
     
  19. BrokenArrow

    BrokenArrow Millennium Member

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    That LANL round may have been chambered 45 times in 30 days.

    The bbl ruptured about midway. This has lead some to believ a bbl obstruction was the cause of failure. If so, some believe the bbl obstruction was a bullet that rebounded from the weakened case mouth area and popped from the case down the bore when chambered, and/or the setback bullet when fired only made it part way down the bore, and the next bullet hit it.

    IOW, so far they don't really know what happened or why, but this sounds good for now.

    From the report:

    On 12 December 2006, at 0845, at Technical Area 72, Firing Range 1, a Glock 22 handgun exploded in the hands of a Protective Technology Los Alamos (PTLA) firearms instructor as he fired the handgun. The firearms instructor was not injured, but felt some soreness in his right hand. He noted that the force of the handgun pushed his right thumb back. The handgun shattered into several pieces; the pieces flew everywhere and eventually landed on the ground. He safed the remaining box of ammunition and then reported the event to his management. As a precaution, the firearms instructor was taken to the Laboratory's occupational medicine facility for evaluation. He was evaluated, released to return to work with no restrictions, and scheduled for a follow-up evaluation the next day. The instructor was preparing for a training exercise and was the only person on thefiring range at the time of the event. He wore the prescribed personal protective equipment for firearms use (safety glasses, armored vest, head and hearing protection, nomex gloves, a long sleeve shirt, and safety boots.) The handgun has been secured in the PTLA armory. PTLA management has initiated an internal investigation. Subsequent preliminary PTLA review indicated that a possible combination of excessive pressure and a bore obstruction contributed to the explosion. The rounds used during this training event were duty rounds recently removed from service that had been used in a magazine containing a single round by PTLA forces. The single rounds of ammunition designated for initial loading in Glock 22 handguns are used on a daily basis and the one round of ammunition is typically loaded 45 times over a 30-day period. The frequent loading of the rounds continually pounds the ammunition into the chamber, which in turn recesses the bullet further into the casing. Over time and use, the projectile is seated deeper into the cartridge case contributing to an increase inpressure upon firing. Because the event revealed lessons learned that may be pertinent to the DOE complex, the Institutional Facilities and Central Services Facility Operations Director deemed the event reportable as a management concern.

    Background: The firearms instructor had used the handgun for about five years.He noted that the last time he used the handgun was on 7 December 2006, and had cleaned and secured the handgun that same day. Before the event, the instructor had fired the handgun five times. After the event, the instructor noticed that one bullet remained in the handgun. Other PTLA firearms instructors noted that this is the first time this type of event has occurred with Glock handguns at PTLA.

    Cause Description:
    Operating Conditions:
    Training Exercises Activity Category:
    Training Immediate Action(s): As a precaution, the firearms instructor was taken to LANL occupational medicine for evaluation. He was evaluated and released to return to work with no restrictions. He returned for a follow-up evaluation on 13 December 2006. The handgun has been secured in the PTLA armory. PTLA management has initiated an internal investigation. The remaining box of single round loading magazine ammunition has been removed from service and will be properly disposed of. PTLA will not use defective rounds for training and will dispose of them.

    FM Evaluation:
    DOE Facility Representative Input:
    DOE Program Manager Input:
    Further Evaluation is Required:
    No Division or Project: Protection Technology Los Alamos
    Plant Area: TA72, Firing Range 1
    System/Building/Equipment: Glock 22 Handgun Facility
     
  20. horge

    horge -=-=-=-=- Lifetime Member

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    Hi Broken Arrow,
    Agreed that simple bullet setback seems insufficient to produce
    the particular catastrophe you describe, and aspects of the
    damage (barrel rupture) implicates some form of bore obstruction.
    Thanks for the additional detail.
    :)

    It would be interesting to know if the investigation tried to measure
    the OAL of other (I presume there were) repeatedly chambered cartridges.


    Hi Allegra,
    Yes, we are indeed talking about a ramped barrel.
    jundeleon indicated he was using proper factory ammo and getting
    noticeable bullet setback after just a single dry cycling,
    hence the suspicion that the ramp wasn't smooth.

    Oliver's right to bring up the roof of the chamber and especially
    magazine seating, although I've seen the same kind of problem
    jundeleon describes (on a less severe scale), with NIB Armscor 1911A2's
    using proper mags (no seating or catch problems), and Hornady XTP's.
    Granted, there are differences between the Armscor A2's and the
    ParaOrd P14.

    :)
    h.