Another 300 black out question

Discussion in 'Handloading and Reloading' started by Jonny2guns, Apr 15, 2021.

  1. Jonny2guns

    Jonny2guns Member

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    I see the 300 BO uses pistol powders, has anyone tried loading with Unique?
    If so, what were your results?
    I have :
    Speer 110gr RNSP
    Horn. 150gr BTSP
    Horn. 180gr SP Interlock
    Plus a few others.
    And of course Unique...
     
  2. Klaatu Barada Nikto
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    Klaatu Barada Nikto Contributing Member

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    Never tried Unique. Accurate No. 9 and 5744 work well for the 300BO.
    Good data Here
     
  3. Wreck-n-Crew

    Wreck-n-Crew Member

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    I havent tried anything outside of published data and dont plan too. If it aint there then there is usually a reason why.

    300 blackout uses magnum pistol powder which is different than pistol powder that works in magnum. But it also uses rifle powder.

    Are you talking about a semi-auto? If so your going to need enough hot gasses from a powder without going over chamber pressure to use in a semi-auto. That means magnum pistol or the right rifle powder.
     
  4. Jonny2guns

    Jonny2guns Member

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    That makes sense, didn't catch the part about magnum powders. Thank you.
    Yes it is a semi auto. And evidently the only powder I have is 1lb of H110.
    Now is not the best time to add a new caliber to the stables.
     
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  5. reddog81

    reddog81 Member

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    I've used unique and in a bolt action and it works well. 5.5 grains with a 200 grain lead bullet gets right at 1050 FPS. It's a great subsonic load. With a jacketed 180 grain bullet I'd suspect it'd work well in a bolt action. I never tried Unique in an AR-15. I'm guessing it'd work OK as a single shot...
     
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  6. kcofohio
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    kcofohio Contributing Member

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    H110 should work well with supersonic loads in a semi-auto. It may or may not with subsonic loads.

    In subsonic loads, most point to faster rifle powders like AA1680, IMR4198, and Reloder 7. I did get 300-MP to work with a pistol AR.
     
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  7. Havok7416
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    Havok7416 Member

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    Follow your manual. Guessing at what powders "should" work is a recipe for disaster.
     
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  8. edwardware

    edwardware Member

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    Lack of curiosity.

    .300BO is classically loaded with petit rifle powders (H110, developed for .30 Carbine) that you think of as pistol powders because they are now in common use in magnum pistol cartridges. They're much slower than Unique.

    Based on my experimenting in .300BO and 7.62x40WT, I predict that Unique is too fast to run the gas system on a semi-auto. It will certainly "work", but you might be at pressure max before you get enough pressure at the port to operate.

    If you're ready to start experimenting, get QuickLoad, and work up gingerly from 60% of predicted charge for max pressure. Worst case, you'll learn things you don't know today.
     
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  9. Jonny2guns

    Jonny2guns Member

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    Good info., and good advice. Thank you.
     
  10. dgod
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    dgod Contributing Member

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    I personally have loaded with CFEBLK, which is a Copper Fouling powder that prevents copper buildup. Meters well and is a solid powder for my application.

    Good Luck
    Dan
     
  11. unwashed

    unwashed Member

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    Exactly, without curiosity we wouldn't have all the wildcats as standard ammo today.
     
  12. edwardware

    edwardware Member

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    I probably won't invent a standardized wildcat, but I have spent many enjoyable hours experimenting with off-manual powder and bullet combinations. Some have become favorites.
     
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  13. EricBu

    EricBu Member

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    I'd just hazzard a guess that unique is a little on the fast side. The powders I use the most for 300 BLK are RL7, Lil Gun, and H110, with RL7 being my favorite.
     
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  14. Jonny2guns

    Jonny2guns Member

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    RL7....I just remembered I have some of that, I'm gonna have to give it a try.
     
  15. EricBu

    EricBu Member

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    That's a good one...works great with the heavies. IIRC, in my 7.5 inch AR I'm running somewhere in the neighborhood of 11 grains of RL7 with full function and last round BHO with and without a suppressor using 200 grain SMKs. Same load I think for Gallant 217 coated. In the 7.5 it's ~950 fps, but these round will crack in my 16in Scout. They are right on the edge of sub in my 10inch AR, and would probably crack on a super cold morning.

    If you're loading for an AR start about 9.5/10 grains at ~ 2.12 to 2.14 coal for a 180 to 220. Ladder until you get full function and last round BHO. If you are shooting suppressed, and you have to have it run with or without suppressor, test unsuppressed first.
    ***Added for Clarity*** The above suggestion is FOR RL7!!!!
     
    Last edited: Apr 17, 2021
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  16. Jonny2guns

    Jonny2guns Member

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    Thank you for the starting point, it is a 7.5" AR. Good to know what you found that works.
     
  17. Wreck-n-Crew

    Wreck-n-Crew Member

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    Are you saying i have a lack of curiosity?
     
  18. Swampman

    Swampman Old Fart

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    Just to clarify here, your 9.5 to 10 grain starting load is for RL7, correct?

    'Cause if anyone tries it with Unique and a 220 grain bullet they're likely to have a BAD day.
     
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  19. Jonny2guns

    Jonny2guns Member

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    That is the way I read it, as in the first couple of post I realized why Unique is a bad choice for this round. But as always, double check for yourself first.
     
  20. Swampman

    Swampman Old Fart

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    I worked down a nice load with Alliant 2400 for my 16 inch, pistol gas carbine.

    7.2 grains of 2400 over a CCI #41 primer in converted Lake City brass will push a homemade, powder coated Lee 230 grain cast bullet just over 1000 fps.

    It functions reliably with my can installed except that it refuses to lock the bolt back

    The load seems quieter than any other powder I've tried in my rifle and best of all, it'll fill over 970 rounds from one pound of 2400.
     
    Last edited: Apr 17, 2021
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  21. Jonny2guns

    Jonny2guns Member

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    I have some 2400, and was wondering if it would work. For some reason Alliant doesn't list any info for the 300BO...at least that I could find.
     
  22. Walkalong

    Walkalong Moderator Staff Member

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    I have used 2400 under 147 Gr pulled FMJs and it works well, so does AA #9.
     
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  23. kcofohio
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    kcofohio Contributing Member

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    That's interesting. I recently had work up loads for 2400 and 300MP with the same cast bullets. For some reason I start my loads in 2400 with higher charges. Like 10.1 gr. What should have been about 20k psi, the primers looked like I was running in the 50k+ psi. I only shot a few. But the 300MP were right where I like them with, IIRC, 9.3 gr.

    I'll need to pull the remaining 2400 loads and start over.
     
  24. EricBu

    EricBu Member

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    I updated to make sure that was clearer! Thanks.
     
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