Need answer on 9mm Mak. brass

Discussion in 'The Ammo & Reloading Forum' started by ransom63, Dec 31, 2011.

  1. ransom63

    ransom63 New Member

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    I've been trimming down 9mm brass for my Makarov reloads. I took some rounds to the range yesterday & they're keyholing. I rechecked my dimensions.The length of the brass SHOULD measure .705" & my resized brass was cut to .700". Also, the crimp standard should be .390" & my crimps are at .387" ( the crimp is done in a 3 die procedure- no seperate crimp die)
    Now here's my question; can these extremely small differences in the brass (.005") AND the crimp (.003") cause the keyholing? They seem to be such insignificant differences from the called out dimensions that I thought maybe there would be that much tolerence for them.
    I've already trimmed about 200 pcs. of brass to the .700" size. Is this brass trash?
    Last edited: Dec 31, 2011
  2. JLA

    JLA Well-Known Member

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    Keyholing is cause by insufficient bullet RPM. 2 ways this can happen.. #1 the barrel simply doesnt have a fast enough twist and the bullets are destabilizing and tumbling to the target. and #2 the bullets are too small for the bore (i.e. youre using .355" bullets intended for the 9mm and .380 in a makarov which normally uses a .365" bullet..

    So which is it?
  3. res45

    res45 New Member

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    I've only experiences keyholing twice in about 30 years and both times it was because the bullet was to small in dia. to engage the rifling,both were with swagded lead bullets that were to small for the bore to begin with.

    The Speer reloading manual has a trim to length of 0.703 and a max case length of 0.713 and that's using commercial Starline brass in a Bulgarian Mak. Hornady list and E. German Mak. with at Max case length of 0.713 and a trim to length of 0.708. I shoot for 0.705 when I trim my case with my Lyman power trimmers but some end up +/- 0.002.

    I shoot a PA-63 chambered in 9 x 18 Mak. and form all my brass from once fire 9mm brass of various brands. I shoot two bullet Speer .364 dia. 95gr. GDHP and cast lead .365 dia. 93 gr. RN. The GDHP and cast bullet both crimp at 0.387 incidentally the Brown Bear FMJ steel case ammo has a 0.386 crimp and the case length measures 0.702" before firing.

    Mak. bores can vary I've seen some as small as .363 up to .366 dia. A little more info on your load data might be helpful in helping to determine the problem ie,bullet dia. and type,powder and charge weight.
    Last edited: Jan 1, 2012
  4. Alpo

    Alpo Well-Known Member

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    I'm gonna have to throw in on "you bought '9mm' bullets, but you bought the wrong size" bandwagon, and say that you are using .355 bullets.
  5. RandyP

    RandyP Member

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    I wouild chime in and add that I have never trimmed a single piece of pistol brass. IMHO it is not necessary in the four calibers I reload.
  6. ransom63

    ransom63 New Member

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    OK, here's some more detail..
    I'm using the Speer .364 dia. TMJ, with Universal powder, 4.1 grns. My crimps are @ .387". The pistol is the CZ 82. I've forgotten what the term is, but the CZ82 doesn't have the typical land & groove bore.
    Can the case length be a factor?
  7. Alpo

    Alpo Well-Known Member

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    No. A too-short case might not fire, as the case headspaces on the mouth, and if it was waaay too short then the firing pin might not reach the primer, or if it did, be at the end of its stroke and not hit hard enough to pop it.

    But keyholing is a bullet/rifling problem. Brass length has nothing to do with it.
  8. JLA

    JLA Well-Known Member

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    Ive never owned a CZ82 9 mak but I have a CZ83 in .380 and it does have a cut rifled bore. Perhaps yours is either very well used and simply shot out or it is the aftermath of an experiment gone wrong.. Might slug the bore and take some measurements. Im bettn you will find it is extremely oversized.
  9. RandyP

    RandyP Member

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    As part of my troubleshooting protocol, how does the CZ-82 shoot with any brand of factory ammo? If OEM ammo doesn't keyhole then at least we can be sure that the problem lies somewhere in your reloading process.
    Last edited: Jan 2, 2012
  10. ransom63

    ransom63 New Member

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    The CZ 82 has a polygonal barrel. The last time I shot OEM, the rounds made perfect round holes, so there has to be an issue with my reloading. It's going to be a couple weeks before I can reload another batch, so between now & then I'll review all my dimensions so everything will be dead-on spec.
  11. res45

    res45 New Member

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    My shooting buddy has the CZ-82,the only commercial ammo he shoots in it is Russian steel case and it does fine with that. His reloads are strictly Lee 95 gr. .366 dia. cast bullets shot as cast,they also shoot just fine. I'm thinking the .364 dia. bullet may just be to small and with less resistance in the smooth bore and being jacketed it's not bumping up enough to stabilize.

    Might want to try out some of the Hornady .365 XTP HP http://www.grafs.com/retail/catalog/product/productId/6339
  12. medalguy

    medalguy Member

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    Mike your bullets and let us know the diameter. I also trim 9mm Para down to use in my Mak and haven't experienced any problems with keyholing. I'd bet on the bullet diameter.
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