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Thread: 300 AAC Blackout... maybe my new most favorite caliber

  1. #11
    Join Date
    Nov 2010
    Location
    Glendale, AZ
    Posts
    1,795

    Default This may be my subsonic load

    After some disappointing attempts to load this round, I think I finally cooked up the correct subsonic load for my barrel lengths.

    Sierra SMK HPBT 220 grain
    IMR 4227 powder; 10.5 grain
    .223rem brass cut and formed, sized and trimmed to 1.358"
    Overall length seated to 2.190", with a light taper crimp.

    I'm pulling an average velocity of 1007-FPS with a 16" barrel. 887-FPS with a 10.5" barrel. Obviously, this is a Subsonic load. Not good for general hunting as the Sierra SMK bullet may not expand very well. Although it's a hollow point, it's really designed for target shooting.

    I had some problems with failure to feed with some of my loads I did to test velocities. Turns out that I had some crappy PMP South African brass mixed in with my Federal, Remington, PMC, and Fioochi brass. It tooks some time to filter out those crappy PMP rounds, as I had prepped over 1,200 rounds of brass.

    Although the original load data had the overall length at 2.600", it had issues feeding from my Magpul Pmags. I think this length was originally set for Thompson Contender barrels and the lengths were originally for the 300 Whisper. The recent data I found has the case length at 2.190" so it does feed better.

    Now that my subsonic load is finished, I need to work a load for hunting. I am considering the Hornady A-Max 110 grain and Speer TNT JHP 125 grain. Both are the most price conscience (under .25cent per projectile), and readily available in most stores. Any thoughts on this?
    2009 4-door JK - 85% daily driver, 15% hunting vehicle, 100% fun!

    It's better to be prepared, than scared.
    Mailman by day, Gun Nut by night.
    NRA Certified Instructor - 5 disciplines.

  2. #12
    Join Date
    Oct 2013
    Posts
    25

    Default

    i haven't been able to find the 110 Amax so i went with the 125gr ballistic tip. It is what PNW arms uses in their 300blk hunting round so i figured i would copy that. http://store.pnwarms.com/rifle-ammo/...box-of-20.html

  3. #13
    Join Date
    Oct 2013
    Posts
    25

    Default

    where were you seeing the 110gr amax? im using 125 ballistic tips because thats what PNW arms uses for their hunting rounds and its reasonably priced at 17 bucks per 50 rounds.

  4. #14
    Join Date
    Nov 2010
    Location
    Glendale, AZ
    Posts
    1,795

    Default

    I have not found any 110gr Vmax. I just saw the load data so I thought I would try to find them. No luck. I did buy 200rnds of 125 ballistic tip and will work with that. My Hornady case prep center took a dump on me. It's going to get shipped back tomorrow for some new gears. In 2 weeks I will start up again.
    2009 4-door JK - 85% daily driver, 15% hunting vehicle, 100% fun!

    It's better to be prepared, than scared.
    Mailman by day, Gun Nut by night.
    NRA Certified Instructor - 5 disciplines.

  5. #15
    Join Date
    Oct 2013
    Posts
    25

    Default

    does your subsonic load lock back the bolt after the last round?

  6. #16
    Join Date
    Nov 2010
    Location
    Glendale, AZ
    Posts
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    Default

    It does lock back. However I am finding that I'm getting a lot of blowback. I'm getting sandblasted by debris coming out of the ejection port. It may be unburned powder. I'm debating if I want to risk dropping the powder charge from the min of 10.5 to maybe 9.5.
    2009 4-door JK - 85% daily driver, 15% hunting vehicle, 100% fun!

    It's better to be prepared, than scared.
    Mailman by day, Gun Nut by night.
    NRA Certified Instructor - 5 disciplines.

  7. #17
    Join Date
    Oct 2013
    Posts
    25

    Default

    i'd try it. Worst case you have to pound out a squib stuck in the barrel. Not THAT big of a deal.

  8. #18
    Join Date
    Oct 2013
    Posts
    25

    Default

    shot my supersonic (hunting) load yesterday. At 50yds my best group was probably 3 inches so it definitely needs some tweaking. I might make the OAL longer and add a crimp to it and see if that helps. Here are pictures of the target and a closeup of the best group.




  9. #19
    Join Date
    Nov 2010
    Location
    Glendale, AZ
    Posts
    1,795

    Default Using a 9mm suppressor for the 300 Blackout (subsonic)

    I was flipping around www.300BlkTalk.com and found several postings of guys using their 9mm suppressor to run subsonic 300 blackout rounds. This was interesting to me as I was about to spend $600 for a 30cal suppressor and $200 for the federal tax stamp. Instead, I was able to order a thread adaptor to convert the 5/8-24 threads on my barrel, to 1/2-28 to match my AAC Evo9 suppressor. A steal of a deal at $40 for the adaptor, and I picked it up from DSK Armory. The one that have looks like this, but is matte black finish.

    Name:  muzzle-thread-adapters.jpg
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    I was still skeptical about this, so I called AAC (advanced armament) and they verified that I can shoot subsonic 300 Blackout rounds out of the 9mm suppressor, so long as it's not full auto or crazy pressures.

    Good news!
    2009 4-door JK - 85% daily driver, 15% hunting vehicle, 100% fun!

    It's better to be prepared, than scared.
    Mailman by day, Gun Nut by night.
    NRA Certified Instructor - 5 disciplines.

  10. #20
    Join Date
    Oct 2006
    Location
    Mesa
    Posts
    6,430

    Default

    Thats awesome! Do you need a stamp for each suppressor?
    Touch the cow. Do it NOW!

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