Some observations on 357 sig and bullet setback

Discussion in 'Reloading' started by nutsnax, Aug 6, 2020.

  1. nutsnax

    nutsnax

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    So I've reloaded thousands of rounds of 357 sig at this point, thousands of 9mm and 40 etc.

    I never NOTICED setback issues until I tried setback testing on every one of my loads from my latest batch of 357 sig.

    I used a decent amount of force and pushed the projectile against a desk top.... the results were concerning.

    ~30% of my loads resulted in the projectile fully setting back into the case rattling around... and this was with a mix of 357 and .40 brass.

    I use a Lee Loadmaster with FCD. I only barely flare the case mouth.

    Then I tried something else....

    I had a pile of nickel plated .40 that I'd processed. I knew it was harder and prone to neck cracking when being formed but I decided to form it anyway and load it to see if it had the same setback issue. The theory being that the nickel plating is less "stretch-prone" and therefore should retain tension better.

    The results were incredible. That 30% number went to around 3%

    I tried the same test using spent steel tula .40 cases I had scrounged from the range and polished the ever loving sh!t out of them and oiling before forming on a different die set I had laying around. That number went to zero percent though I only did about a dozen because I know steel is hard on dies.

    It seems that neck tension on this cartridge is very material sensitive....

    has anyone else noticed these sorts of results?
     
  2. mcmetal

    mcmetal

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    I guess that is why a lot of folks use accurate #9 for 357 sig. I don't think it's possible to consistently protect against setback with 25 pounds of pressure without powder supporting the bullet.
     
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  3. 9x45

    9x45 Millennium Member

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    Yes, you didn't mention what bullet you were using, material, diameter, shape, and whether or not the brass was once fired .357SIG or formed from 40S&W, or what powder and charge weight used, but all that matters for .357SIG. It is the most sensitive to setback because of the very short neck, but usually the powder type and charge weight occupy most of the case volume. I loaded over 12,000 rounds of that using 125 JHP Montana Gold and 125 HiTek Bayou over 8.2 grs of BE-86 in once fired indoor Speer brass. Not one setback, but I've tossed out factory rounds that have had setback. The 151 gr Blue Bullet on the right was just a sample of 10, didn't work out so well, but I have friends in Australia who shoot 180 gr bullets in .357SIG as a standard IPSC Major load.

    [​IMG]
     
    Last edited: Aug 6, 2020
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  4. nutsnax

    nutsnax

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    thanks for the reply!
    Sorry i didnt specify the other items.
    Im using a 95 grain TJ conevera FMJ in this case.
    I'm using titegroup so there is no powder cushion (7 grain), I'm using both a mix of newly formed .40, existing formed .40 and fired 357 sig brass (unsure as to how many times as i got them from a friend). No brand new 357 sig brass.
    Ive heard of new underwood loads exhibiting setback.
    Brass casings exhibit the highest rate of setback. The nickel plated exhibit far, far less and the jury is still out on the formed steel casings though i expect it to be at or near zero from what ive seen so far ( i cant make the the things set back as much as i try).

    I appreciate your input, thank you!
     
  5. 9x45

    9x45 Millennium Member

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    Don't use TiteGroup for .357SIG!!! There is not even any published load data at Hodgdon for that! TiteGroup is a very high density, very low volume, fast and hot powder. There is zero margin for error. Internal pressure is affected greatly by the slightest change in case volume or charge weight, which means OAL is also critical. And don't use .380acp bullets in a .357SIG!!! That is most likely the cause of your setback because the diameter is probably not .356", at least not with any FMJ .380acp I ever measured. And don't use steel cases! In fact, I don't even know if steel cases come in 357SIG. And don't use any press that can short stroke and double a charge with TG. My buddy recently blew up one of his G17's loading on a Dillon 550 (manual indexer) watching the grand kids pulling the handle. 6 grs of TG blew it to pieces! Now I have a 550 from 1986 but never use TG on it, that's for the SD because it cannot run backwards.

    .357SIG requires a very low density high volume slow burning powder like HS-6 or BE-86. Loading with TG is asking for a KB. Only powder makes test pressure, so only published loads should be used.
     
    Last edited: Aug 6, 2020
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  6. nutsnax

    nutsnax

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    good Lord 6g of TG in a 9mm? I thought I was running hot at 7g but that sounds bonkers in a 9mm. I didn't think the 9mm casings could even readily handle that?

    I already blew up a polymer80 frame with it, though this was on an unsupported 357 sig chamber with the projectile set back into the case (no more rockslide barrels for me!). My fully supported lone wolf barrels run fine.

    Previously I'd been running Herco and just recently got some titegroup so I can switch to something else.

    I will never run a chamber that's not fully supported again. I'll look into those powders you mentioned.

    Thank you for your input I appreciate it!
     
  7. George Kaplan

    George Kaplan emeritus

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    You measured something? LOL!
     
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  8. Mr Meeseeks

    Mr Meeseeks

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    At 13.6 grains of AA9, I don’t have any problems with setback. As a matter of fact, the load is so compressed that the bullets want to creep forward overnight if the dies aren’t set just right. A true .357 diameter bullet helps with neck tension too. Also seems to increase velocity, pressure, and... mechanical accuracy.

    * The above discussion is a hypothetical load used by a blue cartoon character on the internet. Attempts to replicate said load without careful work-ups could result in Beruit style KaBooms.. Though the slow burn rate of AA9 does make it pretty difficult to blow yourself up. My pistol has a 24# spring and still throws brass a ways.
    —-

    As far as soft loads of sig with titegroup, I’d only ask, why? Might as well use much cheaper 9mm brass at that point. Also, don’t form sig from 40 brass, unless it’s an apocalypse survival situation.
     
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  9. Jed Cooper

    Jed Cooper

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    I converted a G31 & G32 to 40cal for all the reasons above. I just got tired of setback even with factory rounds PLUS the ammo cost. Feeling I had to feather the slide down into battery on a 357sig round to avoid potential setback is insane.

    Great round otherwise.
     
    Last edited: Aug 7, 2020
  10. 9x45

    9x45 Millennium Member

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    Yea, AA#9 sounds like a good load. Here is the 125 FMJ data.
    125 SIERRA FMJ 11.7gr 1,220fps 13.0gr 1,387fps 39,100psi 1.140"OAL

    actually a 9x19 case can hold almost 12 grains of TiteGroup. And even at 6 grains, it's very hard to see that in the case.
     
  11. 9x45

    9x45 Millennium Member

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    Yes, it's true. I do measure bullet diameters with my 50 year old Starrett tenths micrometer. None of that digital stuff for me! Vernier has the feel, digital's don't. And OAL with my German made vintage Helios dial calipers. However I will confess that digital scales are the bomb compared to balance beams. So i use a $25 Gem 20 jewelers scale from Amazon for pistol. And before I retired I made up a couple of dozen calibration check weights, out of aluminum wire, at 3-6 grains, using the $20,000 vacuum lab scale capable of +/- .00001 grains.
     
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  12. nutsnax

    nutsnax

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    Ive done virtually nothing but form 357 sig from .40 and oddly enough the formed 40 cases set back less than the 357 sig cases in my experience.

    Has anyone tried to lacquer the mouth of the case to help prevent setback like on certain russian cartridges? If so what was your experience?
     
    Last edited: Aug 7, 2020
  13. 9x45

    9x45 Millennium Member

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    You don't want to use paint to increase neck tension, you want the bullet OD to provide enough interference fit with the case ID. What is the diameter of your 95 grain bullets? What is the ID of your formed from 40S&W case?
     
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  14. nutsnax

    nutsnax

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    Here is what I measure - hope I'm not doing something wrong?

    IMG_20200808_145000017.jpg IMG_20200808_144909671.jpg
     
  15. Taterhead

    Taterhead

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    Tough to get a good ID measurement that way. For the neck ID, it would be easier to measure the OD. Then subtract twice the average thickness of the brass.

    Alternatively, measure the neck OD prior to seating, then measure it after seating. The difference is the amount of neck tension, assuming the bullet doesn't swage.

    Another useful measurement is the diameter of the shank of the expander. Allowing for maybe a thousandth of springback, that should be the neck ID.

    Lastly, be sure that the heel of the bullet is not wider than the shank of the bullet. Otherwise it acts like a neck expander as it passes through the neck.
     
  16. nutsnax

    nutsnax

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    I took the caliper and spun the case around on it while applying outward pressure and took the widest measurement. I'll have a try with your method and compare the two.
     
  17. Mr Meeseeks

    Mr Meeseeks

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    The neck has less surface area because it’s shorter. This is real 357 sig brass. You want to make it you need to trim 10mm brass. If you can get ahold of some real 357 brass I bet you’ll automatically get a little more neck tension.

    ED551BF6-8467-4C00-AB75-CF99CC9DBB4E.jpeg
     
  18. nutsnax

    nutsnax

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    I have ~1500 357 sig brass cases.

    I measured OD and then wall thickness and my ID measurement jives with it - I just rotated and manipulated the case around in a circle along the caliper and took the fattest measurement (though I probably should have taken an average of multiple points but oh well).

    The case illustrated above I just loaded and I cannot make the thing set back no matter how hard I push the projectile on to the desk from the base of the case. I'm a 200lb+ guy so that shouldn't be the problem (I hope) - though if that's the issue then I've got a lot bigger problems. This is with 7 grains of titegroup also so I'm not running into powder.

    I can't even get the formed nickel .40 to shave a thousandth off of the COAL. This is the case with the rest of my nickel plated stuff.

    I can usually get my 357 sig brass (or formed brass .40) to give up a thousandth or completely set-back.

    So either I'm a 200lb weakling, this nickel plated brass I got is freakishly strong or the properties of nickel make it better suited for this type of application where maximum neck tension is required.

    My brass .40 and 357 sig consistently measure at ~.350 ID or thereabouts.

    If I had more steel I'd measure that but I don't.
     
  19. George Kaplan

    George Kaplan emeritus

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    Great tip measuring the expander shank.