9MM Brass—How Short is Too Short?

Discussion in 'Reloading' started by xTerpx, Jun 16, 2020.

  1. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    In continuing with my series of asinine newbie questions, I have another three I couldn't find the answers to on my own. :)


    1.) What causes 9mm case length to shorten?
    • I guess it's just rifle/shouldered cases that lengthen when shot? I am assuming getting slammed by the breech face into the ridge to headspace at the mouth is the culprit? Is is usually more noticeable after, say, 5+ reloads of the same case?
    2.) How short is "too short"?
    • I've been studying my SAAMi specs and assuming the .754 is the max length, more or less, but what is the minimum? I have a few that seem much shorter than others and assuming no one trims 9mm brass nowadays, so wanted to ask.
    3.) If a shorty slipped by me, what's impacted?
    • During one of my overthinking sessions, I thought 1.) the bell will be jacked up if set for 'regular' sized brass...not as deep...or does the resizing die ever-so-slightly stretch it (thought it just re-forms the case shape, but I don't know) and 2.) the crimp (removing the bell) would be impacted, too...and thought 3.) the bullet won't be seated as far, being shorted by how much shorter the suspect case is relative the case I used when setting the OAL.

    I had (have) zero plans running plain brass through case gauge, but was checking a few cases and some factory rounds to get a feel for it and I assumed none would pass (thought looser glock chambers would expand them very slightly, but enough to fail the case gauge toward the head...some did fail like that...but some didn't.

    Some of the cases were short in the cause gauge, which raised the flag. The smallest case was .735 and just looked small enough that I checked the headstamp thinking .380. Some felt really light, too, and were also short...but all was 9mm.

    Not knowing better, I would probably have shot most of the short ones, as they were just recessed a little but not as much as the .735-.740s...would have tossed those. HOWEVER, without case gauging the brass before loading, I am not sure I would have caught them.

    I also thought though the case is shorter, it isn't necessarily a pressure concern, right? I am assuming to maintain the same OAL as the rounds with the full-size case, the bullet would be seated less deep and offsets the shorter case? (though not a linear relationship I am learning).
     
  2. SARDG

    SARDG Florida's Left Coast

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    ...my head is about to explode. You don't want to be responsible for that, do you xTerpx?? :cheers:
     
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  3. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    I hope you're not noticing a pattern...that these type of questions come after midnight when I have my calipers out while enjoying adult beverages. :)
     
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  4. Schrag4

    Schrag4

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    I would think you'd get less bell, which may or may not make getting bullets to set straight on the belled case before seating more difficult. Depending on what projectiles you're using, might also be an issue - FMJ, no biggie, but coated lead might get some lead (and coating) scraped off on the way in if it's not belled enough.

    I'd think there would be no difference in removing bell. The bullet's OAL during seating should be the same, which I suppose is "less deeply" seated, but that should only impact how much tension there is holding the bullet in place. Same case volume, so probably not an issue.

    I would think that BY FAR the biggest detriment to loading a significantly short case would be that the short case may not give the powder drop a full stroke. I had a 380 case make its way onto my turret press while loading 9mm recently, and it took me a minute to realize that I wasn't getting powder because it wasn't moving the disk far enough to put the cavity over the powder-through-flare die (or whatever it's called). It would have been much worse if it dropped, say, 1/2 or 2/3 of the powder and if I didn't catch THAT.

    I would think that a really short case would also not be great for firing since 9mm headspaces off the case mouth. If it was short enough, that would change to the extractor being what prevents the cartridge from moving further forward in the chamber, right? I'm sure that would have its own set of problems, although perhaps none of them catastrophic, maybe just light strikes and terrible accuracy.

    I'm sure someone will come along and set me straight.
     
  5. unclebob

    unclebob DFC, MSM, 12 Air Medals.

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    Why is it that you can shoot .40 in a 10mm and 45gap in a 45acp? So is the case being held back by the extractor or head spacing on the case mouth? Or like what my neighbor did and shot 9mm short in a 9mm. Which is 380. And wondered why he had well belled deformed cases.
     
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  6. sciolist

    sciolist On the Border

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    Focus on your breathing. You just have to make it through to the point where he actually starts productive loading.

    On topic, the only negative I've seen from shorter range cases is they sometimes don't actuate the bullet dropper, so I place a bullet manually.

    Bell isn't really a factor, because I'm really only using the expander portion of the MBF die.
     
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  7. Jim Watson

    Jim Watson

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    I have never done anything about case length for an auto caliber.

    Anecdote Warning 1.
    I once got some Boxer primed Makarov brass in with 9mm P. It would run right through the Dillon and I would not notice a thing until I was gauging the finished ammo and see a lot of bullet showing or have it drop way down in the gauge. So I would pull them down to salvage the components and trash the case.

    But one day I wondered, WILL the extractor hold headspace? So I saved the next couple that came along and loaded them in a gun. They fed, fired, extracted, and ejected normally.

    Anecdote Warning 2.
    Cases too long are very uncommon but I once picked up some Hornady Frontier .45 ACP that mystified me by refusing to let the slide close on reloads. I finally got around to measuring them and found them over length. The original purchaser must have had a generous chamber.
     
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  8. 9x45

    9x45 Millennium Member

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    xTerp, you are way, way, way overthinking this.

    1) Pistol cases do not shorten during firing, they get longer but only by a few thousands after multiple loading. A short(er) case just was made that way.

    2) Yes, .754" is a SAAMI standard, but not all ammo is made to SAAMI. S&B for example. I just measured a hand full of once fired indoor LEO range WW brass at .740"-.745".

    3) All NO's. Sounds like you are using mixed brass, most likely range pickups. Why don't you buy 100 brand new brass and set up on that. The only thing that changes during reloading is the brass, not the resize, not the powder thru, not the seat, not the crimp. So if you have a .755" case it will get more bell than a .740", but the crimp will be the same as it is just a taper. Mark the brass with a permanent marker and you can see what gets wiped. There will always be slight variations in powder thru bell because of that.

    There is no reason to case gage resized brass, it won't tell you anything. 99% of all reloads that don't case gage, or plunk test, a loaded round is on the front end. The OAL is too long for that particular bullet, or too much bell, followed by too much crimp. Then what? a bulge because the brass has nowhere to go with heavy bell or heavy crimp. Only enough bell to "SET" the bullet, not seat, the seating die will do that, and only enough de-bell (crimp) to case gage, no more.

    And don't get all detailed with bell and crimp measurements. Then get your OAL right for your bullet, and start pulling the handle. Look in each case at station 3, but don't weigh out charges. Dillon powder hoppers will always throw (depending on powder type, sugar or corn flake) between +/- .1 grains to +/- .3 grains. This will make no difference in accuracy even out to 50 yards.

    And don't change anything! Unless you switch powder or bullet type, just keep pulling the handle.

    This is a 124 gr HiTek coated Bullet at .3556" diameter at station 3 (seat). 3.3 grains of TightGroup at 1.100" OAL, chrono's about 1,050 fps to make USPSA Minor of 125 floor. Try to find even the slightest bell on the case (.742" lenght). That's all you need to set. It looks like their is no bell at all...

    [​IMG]

    Now station 4, showing the seated bullet before de-bell. Still looks like there is no flare... although it will not case gage at this point until after crimp.

    [​IMG]

    final loaded round, hardly a trace of crimp, which is all you need. By the way, crimp does not hold the bullet in the case, neck tension does. This is the interference fit between bullet diameter and case ID. Over crimping can lead to bullet setback, especially on 9mms.

    [​IMG]
     
  9. 9x45

    9x45 Millennium Member

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    XTerp, ok, last piece of advise. Look up the nearest to you competition club on USPSA.or or IDPA.org. Call the match director, tell him what press you have, and ask if one the experienced shooters would be willing to help you get going on loading. That way you get 50 years of experience in 5 minutes. I have setup up newbies on 550's and Square Deals in under 3 minutes. My kid has setup up newbies on 650's and 1050's in under 10 minutes (more stuff to adjust).

    Then, really important, DON'T change anything.
     
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  10. F106 Fan

    F106 Fan

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    It is also possible to shoot a 9mm in a .40 S&W. It's not a good idea and the case will certainly bulge a bit but it is pretty clear the cartridge is held to the breech by the extractor.
     
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  11. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    Nice. :) For her sake, I am putting off .223 and precision rifle until late Winter when I start knowing enough to be dangerous (and safe). Lots and lots of concepts I still don't have a command of.

    In skydiving, we would ask rookies doing their first jump whether or not they feel they could save their own lives if they had a malfunction...and they way in which they answer determines if they are cut a little slack or held on to the whole jump.

    Similarly, I ask myself whether or not I feel I could produce some rounds without a kaboom or killing myself and I think I am ready...though I still have a million questions and will not be pulling the handle for another week or two. lol
     
  12. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    I actually feel really good about setting it up and dialing it in perfectly. Dillon's "Gary videos" and some other reloading ringers have been extremely helpful. No worries there whatsoever.

    It's the stuff I don't know that concerns me...and a case being extremely short in the case gauge wasn't in any manuals...just trying to get some tolerances to keep me out of trouble. :)

    Yea, as an RO on a military base, I have access to a lot of reloaders to pepper with questions, too...all the old guys on the 1K range all seem to reload, of course. I'm just concerned when I get 10 different answers (or no one has an answer). lol
     
  13. sciolist

    sciolist On the Border

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    Friend of mine that moved out here a few years back has lots of pistol experience, primarily defensive, but basically no competitive or loading background. So we got to work on him.

    He was resistant to loading at first, then got a bolt gun and got sucked in by that crowd. He disappeared into the 1,000-yard zone for a few months and returned to pistol wanting to load.

    No prob, I helped him out a bit with his 550. Then I started getting texts with group pictures. Then more texts with lots of group pictures, and crazy tabulations all over the place. Like, changing OAL a thou, or whatever. I kept telling him to just load and shoot the damn gun...

    It got to the point where he didn't have time to shoot anymore. He was making 3 round trips to the range every day, screwing around with pistol groups, like it was a sniper rifle. I think his wife got pretty close to filing.

    Fortunately, circumstances presented where he had to take some time off, and everything got reset to normal. At the peak, he was basically out of his mind.
     
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  14. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    Thanks. I can relate. I feel like John Nash (from a Beautiful Mind) sometimes and we have a lot in common. :)

    The 1K guys sucked me in, too...few things rival the feeling when you get on paper at 1K yards for the first time...then you catch the bug. I'm working my up to 6.5, but reserving all those questions for months and months while I study.

    IMG_0661.jpg
     
  15. F106 Fan

    F106 Fan

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    The SAAMI spec is clear: Brass length 0.754" - 0.010" so the minimum length, according to the standard, is 0.744".

    Document page 27 (PDF page 36) here:

    https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf

    Ordinary printer paper is on the order of 0.004" thick so we're talking about a tolerance of about 2-1/2 sheets of paper. Just to keep things in perspective.

    What you can get away with is a different question. I don't know the answer but I do know that I have never measured a pistol case.
     
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  16. 9x45

    9x45 Millennium Member

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    KaBooms don't kill people, in fact (not revolvers or rifles), the worst is usually a couple of stitches and a hurt wallet. I eye witnessed dozens and KB a couple myself (not Glocks). But I read where you have a 25% chance of dying on your first jump????
     
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  17. F106 Fan

    F106 Fan

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    .223 for blasting is pretty easy to load. Case trimming will likely be required and the Dillon trimmer does a nice job in a great big hurry. I can size and trim about 1400 cases per hour on the 650. The trim die IS a small base die so there is no need to resize on yet another die. I do the actual loading on a 1050 because it will take care of crimped primer pockets.

    .223 is easier in the sense that it is impossible to get a double charge without powder spilling all over the place. It's harder in the sense that it takes a relatively long time for the powder to transfer into the case. Have to hold the handle down a little longer. A definite 2 count or some such scheme. Having a powder charge alarm (on the 650 or 1050) is a definite advantage.

    For me, .308 precision rifle is easier in the sense that I use an RCBS ChargeMaster to dispense every charge and I re-weigh it on a Dillon D'Terminator. The actual loading is done on a Redding T7 turret press, one round at a time, with Redding Competition dies. Case trim is important but, for the M1As, shoulder location is everything. The rifle tears up brass anyway but if the shoulder is off a bit, the brass might only survive a single reload. M1A precision in the sense of a Super Match that can really shoot!

    .308 for my Rem 700 is made the same way except I only resize the neck, not the entire case. As a result, trimming may not be necessary or even desirable.

    At some point, I will move the M1A reloading to my 650. The Rem 700 .308 and the F-Class 6.5x284 Norma will remain on the T7.
     
    Last edited: Jun 16, 2020
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  18. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    I got 3K new cases in the garage and 1K from another manufacturer en route to compare...going to start with new brass and track their progress from birth to death.

    My only concern with new brass was many, many report sticking to the powder funnel on Dillons...harder handle, less smooth, brass shavings type of complaints. I'll use some One-shot and see if I notice a difference.

    I know I overthink everything, but planned to use tumbled once-shot while making a bunch of dummies and dialing in the dies, then I'll have a feel for the difference between new vs range brass. :)


    Sage advice, thanks! Of course I bought a bunch of different bullets in all shapes and sizes (.355 vs .356, RN, TC, TCFP, coated, plated, jackets, et al ), so will be doing a lot of changes up front...which I welcome, as I will learn with every change of the die...coupled with multiple powders...but once dialed in to 2-3 favorite loads, I'll pick one and run with it...not changing a thing (bought stands to get toolheads setup with favorite loads so I can just plug and play (and confirm nothing changed, of course)).


    Yea, that's counter-intuitive and still grappling with this one...overcrimpping making it looser. As I am dialing in the dummies, I planned to pull the bullet and check for signs I have it a hair tight...and have my trusty calipers nearby to check the mouth before being flared and after removing it, of course. :)

    Thanks again to everyone for sharing their knowledge...grateful for the good stuff.
     
  19. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    Ummmmm, no. :)

    I haven't check USPA stats in years, but used to be like 0.00005% (would have to do the math to check the decimal placement)...like a dozen bounces (deaths) per 3-4 million jumps. The odds are forever in your favor.

    (And honestly, those deaths are primarily complacent advanced jumpers getting fancy and screwing around doing maneuvers they were taught not to perform at certain points in the dive.)
     
  20. xTerpx

    xTerpx Preferred Pronouns: (It, Ya'll, Bruh)

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    God bless you, sir...precisely what I had hoped for. That SAAMI publication will keep me entertained for weeks. :)

    I keep forgetting the paper thickness perspective...saw a few posts by you referencing it and have it in my notes. It is indeed the 0.00XX that gets me into trouble, not realizing that the difference that far out is barely noticeable, if at all, with the naked eye.

    However, in this instance, I am comparing a regular .754 to an anomalistically ($7 word) .735, roughly a 0.02 difference, which seems material to me...but the general consensus seems to be not to sweat it....and I can see this perspective, because OAL will still be the same...and longer is better than shorter (that's what she said).

    Thanks again, sir.