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Thread: Patching a 9mm to 380

  1. #1
    Boolit Master
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    Patching a 9mm to 380

    Just wondering has anyone tried to patch a 9mm 115 gr up to 380? I would think such bullet would be a good self defense thump-er. (litt'l more weight'er than a 95)

  2. #2
    Boolit Grand Master Nobade's Avatar
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    What does the patch do? They are the same diameter to start with. Just load your 380 cases with heavier bullets and see if you can get them to function through your pistol.

  3. #3
    Boolit Master MOA's Avatar
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    This is from a RCBS 115 grain mold. It is listed in the RCBS #1 reloading manual for use in both the 380 auto and the 9mm. I load it in both.




    For those of you out there who have never seen the RCBS reloading manual this is what it looks like. It goes back a few years, so with all the changes in powders a work-up is important.

    Last edited by MOA; 06-29-2022 at 07:24 AM.
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  4. #4
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    Soooo you want to go from .3555 to .380 for the 38-55 cartridge?

    Should be no problems except getting the paper to stay on the bullet because
    of the short shank.
    And the twist rate may cause the bullet to tumble.

    Mike
    NRA Benefactor 2004 USAF RET 1971-95

  5. #5
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    You will run right into your user name attempting to get a 115gr to work in a 380 SUCCESSFULLY. If it could be done safely, the industry would have been making those for decades.
    Got a .22 .30 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throats honed? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? 480 Ruger or 475 Linebaugh cylinder that needs the "step" reamed to 6° 30min chamfer? Click here to send me a PM You can also find me on Facebook Click Here.

  6. #6
    Boolit Master
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    A .380 Auto or .380 ACP is another name for the 9mm Corto or 9mm Kurz, 9x17, 9mm Short. It is has a 'nominal' .355 diameter bullet like the 9mm Luger or Parabellum. Some 38-55 rifles use a .380 diameter bullet but the .380 ACP uses .355/.356/.357. I have used the Lee 358-105-SWC with great success in the .380 ACP. Heavier bullets MAY work with careful load development, but you are a REALLY slowing velocities with heavier bullets.

  7. #7
    Boolit Buddy
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    Like Doug said, if 115gr bullets worked well in 380ACP, you'd be able to buy them as factory loads.

    The simple fact of the matter is that the 380ACP doesn't have enough powder capacity or working pressure available (SAMMI Max of 21500psi vs 35000psi for 9mm) to drive a 115gr bullet to a useful velocity. Trying to do so is asking for problems.

    If you want a 9mm, buy a 9mm. There are lots of choices that are not much bigger than a 380.

    Buffalo Bore also makes a 100gr +p hard cast flat-nose that is a potent load. Recoil is harsh out of something the size of an LCP, though. It's also kind of hard on the guns in my experience, so its a "load in carry mags but shoot infrequently" sort of a deal.

    And yes, they're both 0.355, so patching is unnecessary...

  8. #8
    Boolit Master
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    There WAS data in the 1971 Lyman reloading manual for 115s in .380. That page is the only one missing from my copy of the manual. Velocities WERE low, but not unworkable. They would be ideal for a suppressed firearm.
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  9. #9
    Boolit Buddy
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    There is still data for 115gr bullets in the 380ACP in the Lyman 50th, but velocities with MAX loads are in the high 800fps to low 900fps range from a 3.75" test barrel. Actual velocities in something like an LCP would probably be low 800's. I'd be surprised if a 115gr JHP designed for 1100fps would even expand at all at that velocity. If it did, it wouldn't penetrate much.

    380 is always going to be a compromise. It just doesn't have the juice to do what a 9x19mm can.

  10. #10
    Boolit Grand Master


    GregLaROCHE's Avatar
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    Have you considered powder coating them to gain a little more diameter?

  11. #11
    Boolit Master MOA's Avatar
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    Velocities shown in fund's manual.

    700x and Bullseye get you close to 900 fps in the testing. I think the testing used a 4" Browning pistol. My biggest challenge was a overall length fitting in the magazine. A number of adjustments was required.





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  12. #12
    Boolit Master
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    Quote Originally Posted by DougGuy View Post
    You will run right into your user name attempting to get a 115gr to work in a 380 SUCCESSFULLY. If it could be done safely, the industry would have been making those for decades.
    Many years ago I got truncated 9mm style luger 125 grain bullets to work in a 380 mauser Hsc with just enough power to function the slide. In other 380s they would not work in the magazine. Not saying it is a good idea and I would not do it in a keltec for example. I inadvertently fired them in an Astra 600 and other then very badly swollen cases, function was perfect and recoil was mild. The A600 is a blow back 9x19 gun designed for sale to Nazi Germany.

  13. #13
    Boolit Master Rapier's Avatar
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    I carry a 380 pocket gun only as backup, totally done up for 100% function. I carry Corbon 90gr JHPs, 1050fps the ballistics gel tests show 15” penetration and expansion to .5 inch. This is a cast forum, but… The 380 really needs as much help as it can get in accuracy, velocity, expansion and penetration. Practice and shoot it as much as you can. Cause a backup means a backup, it is all you got when you need it.
    “There is a remedy for all things, save death.“
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    “Never give up, never quit.”
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    There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.
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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check