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Just had my first experience with tumbling/keyholing

Discussion in 'Reloading' started by njl, Sep 5, 2011.

  1. njl

    njl

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    I've been loading Xtreme 147gr plated with 3.4gr Universal (1.120" OAL) for a little less than a year. Nearly all of it's been shot through my G17 with great results. It avg's about 880fps.

    I was testing out some optics on my G34 today, and had two out of maybe 50 of the above load keyhole and hit the target several inches away from the group. With some quick googling, I read that keyholing can be caused by the bullet not being sufficiently stabilized due to being fired at too low a velocity. That doesn't seem a likely explanation here since the longer barrel of the G34 should be giving slightly more velocity than the 17...and I've put nearly 1000 of these through the 17 and not seen this.

    What else might cause this load to work well in the G17 but not in the G34?

    Depending on who's data you believe, I'm either .1gr over max or .1gr under max...so I could try again with 3.5gr Universal...but I'm not sure I want to.

    Other options for increasing the FPS would be WSF (which I don't have), or WST (which I have used). 3.5gr WST at 1.145" gave about the same FPS as the above 3.4gr Universal load. I've read of people going as far as 4gr WST with 147gr JHP.

    Suggestions?
     
  2. WiskyT

    WiskyT Malcontent

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    North Carolina
    Velocity is not your problem. In some cases it could be, but not at near factory velocity.

    Under the thin plating is a soft pure lead core. I have not had good results with plated bullets in my Glocks. I do better with lead. I think a soft plated bullet shoots like a lead bullet, but they are sized by the manufacturer like a jacketed bullet, which they are not.

    I shoot lead at 0.357 to 0.358". I think those bullets are undersized for the material they are made out of.

    Plated bullets used to be a cheap alternative to jacketed. But anymore they are close to jacketed in price. Based on the poor performance, including keyholing, that I've had with plated bullets, and the high cost, I just make my own lead bullets at this point.

    As for what you can do about it, I'd try loading them down a bit or trying a slower powder. I know Universal is thought of as being very close to Unique, in my own use of it, I found it to behave like a faster power. I would try Unique, Power Pistol, or something else a few ticks slower than Universal is loading them down a few tenths doesn't fix the problem.
     

  3. WiskyT

    WiskyT Malcontent

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    Oh, and the other 48 that didn't keyhole probably didn't fly as straight as they might have. I've had similar experiences as yours while tinkering around with lead bullet loads and found that any load that keyholed some of the rounds shot terrible groups overall.
     
  4. Boxerglocker

    Boxerglocker Jacks #1 Fan

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    Lynnwood, WA
    I load a BC moly 135g with 4.0 WST 1.150 OAL. Runs 1000 fps with a sd of 2-3 out of my Spartan. Great, soft, accurate load. Currently working on a 147g FP load also a BC moly.

    That being said, have you benched your load with the G17 at 25 yards. I say this cause I have personally not found a 147g load that does well accuracy wise with a 147g running less than 940ish FPS.
    Are you using your stock G34 barrel? Mine wouldn't do half the groups with the same load that the LWD barrel I had previously.
     
  5. njl

    njl

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    I haven't benched the load at 25 yds...I never have shot well that way. I have shot GSSF-style plate racks at just over 25yds with the G17 and this load and have no trouble knocking down the plates with few if any misses. Even from the G34, while dialing in the holosight and optima I was playing with today, I was getting very small groups other than the two that tumbled.

    If the sizing of the bullet is the problem, would more pressure/velocity possibly help the bullets get a better seal in the barrel? i.e. do plated bullets deform at the base at all to expand into the rifling...or is that just not going to happen?
     
  6. Boxerglocker

    Boxerglocker Jacks #1 Fan

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    Perhaps if oversized, but undersized I doubt it. I would highly suggest rechecking you die setup particularly your crimp. I would venture to say chances are your overcrimping a tad.
    When at a match scoring, I see a lot of guys with tumbled rounds on the targets. 99% of the time I say check you crimp and it's the issue. I even keep a set of calipers in my range bag just in case it come up.
     
    Last edited: Sep 5, 2011
  7. njl

    njl

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    I'll check the crimp to make sure it didn't somehow come out of adjustment, but I've always been very careful to have the crimp just remove the flare done by the powder die and not crimp enough to leave a mark even on soft plated bullets.
     
  8. njl

    njl

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    No...I'm using a Dillon set of dies on an RL550B.
     
  9. njl

    njl

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    I just measured some bullets and took apart one of my 147gr cartridges. The X-treme 147s seem to be the same size as the PD 124gr FMJ and MG 124gr CMJ I have. Depending on whether you want to believe my digital or dial calipers, they're all either .355 or .356.

    The cartridge I took apart, the bullet also measured the same as above...but there was the slightest bit of visible crimping of the case mouth into the bullet. It wasn't measurable, but looking at it closely in the right light, you could tell where the mouth had been. I guess I'll try backing off the crimp die just a bit. I may also go back to seating these a little longer (like 1.145 rather than 1.120).

    BTW, the G34 is all stock other than sights/optics.
     
  10. Wash-ar15

    Wash-ar15

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    Different guns, different barrels. like BG, I have found that its better to push them 147's into the 925-950 and up to get the best stability and accuracy. Even some factory 147's ,like the HST's, go close 1k fps.

    Bump it up slightly and see what happens.
     
  11. unclebob

    unclebob

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    Oct 14, 2000
    Mary Esther FL
    I had key holing one time from when I sized the cases in a Lee U die on a single stage then loaded them on the 650. Everything else was the same. I also one time had a bad batch of bullets. I sold them to two friends of mine and they had the same problem with those bullets. I weighted and measured those bullets but could not find anything wrong. It was like one in 100+ bullets that was screwed up. Have not had any problems with the X-treme bullets before then or since then. When I was using the 147gr. bullets I loaded them at 1.140. The 135gr. X-treme bullets that I use now are at 1.120.
     
  12. njl

    njl

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    Yeah...they're different guns and barrels, but both are stock Glocks, so it surprised me to see keyholing from the 34 when I've never seen it from the 17. It's not like one's a Glock and one's a 9mm 1911. i.e. very different barrels with different types of rifling.

    I did some more googling last night, and at least one source claimed that the 147gr bullet, being harder to stabilize, needs to be shot at high subsonic velocity to reliably stabilize.

    My avg velocity with 3.4gr Universal is about 10-15% below factory velocity, and of course there's going to be the occasional slower one doing 860 fps or even less. I just would have thought longer barrel of similar type = higher velocity, which would do a better job of stabilizing the bullets.

    I may load some up with as much as 3.8gr WST at 1.145 and see how those feel and perform. 4gr WST is the max I've seen anyone post about with 147gr jacketed bullets.
     
  13. WiskyT

    WiskyT Malcontent

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    Glocks and most 9mm's have a 1 in 10" rate of twist which is much faster than the typical 38/357 rate of twist of 1 in 18" with the 38/357 stabilizing much heavier bullets at lower velocities.
     
  14. tac_driver

    tac_driver

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    Apr 25, 2008
    I don't know if this will help:

    firearm - Glock 19
    bullet - berry's 147gr PRN
    Powder - universal clays 3.5grs (MAX 3.5/924)
    Powder density - 75%
    primer - WolfSP
    crimp - .377
    OAL - 1.150"
    Velocity:
    lo - 901
    hi - 920
    Avg - 913
    PF - 134
    I never had a problem with tumbling with this combination.
    The primers show some signs of flattening with this charge.

    I'm surprised you aren't getting higher velocities, with the longer barrel length and shorter OAL in the G17 and especially in the G34.

    I would suggest carefully working up a load for the G34 at a longer OAL.
     
  15. Colorado4Wheel

    Colorado4Wheel

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    I looked up the twist rate needed to stabilize my 155gr Lead bullets at 130pf. It was between 1-19 and 1-28 depending on who you believe. So it unlikely your bullets are not being stabilized. Of course Wisky already said that a little while back. Crimp and/or undersized bullets seems to be your likely culprit. Could be some brass is also thick and it's swaging down a small % of your bullets.
     
  16. I had horrible keyholing with my CZ and 356's. Once I got a 358 mold, everything tightened up.
     
  17. njl

    njl

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    I did some measuring last night, and decided maybe crimping to .376-.377 was too much. The X-Treme 147s tend to be 0.3555. The Win brass I'm using seems to vary anywhere from 0.011 to 0.013, with 0.0125 being pretty common.

    .3555+2*0.0125 = .3805

    So, in addition to backing off the seater so my OAL is now 1.150", I backed off the crimp die so my cartridges are now measuring 0.380" at the mouth. They still drop in/out of the Dillon case gauge and G34 barrel.

    Since I was only seeing keyholing about 1 in 25, I loaded 100 to the above specs, 50 with 3.45gr Universal, 50 with 3.72gr WST, and I'll probably load another 50 with 3.82gr WST. I adjusted the powder measure to that last night, but decided it'd gotten too late to do any more loading.

    I'll hopefully get to test these this weekend.

    I'm kind of torn as to whether I should even bother taking the chronograph. On the one hand, I like to keep track with new/different loads of the velocity. OTOH, if I get tumbling, I'd hate for one of those to take out the chrony. Maybe I'll chrono a couple of each load through the G17, then shoot groups with the 34 with the rest to see if any tumble.
     
  18. oneofthose

    oneofthose

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    Not sure if this helps, but I once had some Frontier plated (don't remember the weight) that ran fine through my glock 19, but did not like my springfield 1911 in 9mm, and made a few keyholes. My research at the time suggested that the thickness of the plating on plated bullets can be somewhat inconsistant, and that certain types of rifling can cut throught the plating at higher velocities, causing the plating to further separate from the lead core after it exits the barrel and keyhole.
     
  19. njl

    njl

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    Sep 28, 2000
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    X-Treme 147gr 1.150" crimp to 0.380" 3.46gr Universal Clays
    G17 889.4 fps
    G34 908.0 fps

    X-Treme 147gr 1.150" crimp to 0.380" 3.72gr WST
    G17 906.6 fps
    G34 922.0 fps

    X-Treme 147gr 1.150" crimp to 0.380" 3.80gr WST
    G17 917.6 fps
    G34 939.7 fps

    The good news is none of these tumbled from the G34. Just to be sure, I fired a few mags of the 1.120" 3.4gr Universal load from the 34 and saw tumbling again.

    Since I changed two things, it's hard to say if it was the seating depth, the crimp, or a combination of the two.

    At the higher end, the difference in felt recoil between the 147gr load and my old 124gr load (which was doing 1100 fps today from the G34) is small enough, I don't know if 147gr is worth the extra $, and it certainly isn't worth the aggravation. I suspect in the future, I'll either be going back to MG 124gr CMJ or maybe try their 147gr CMJ.