Subsonic Ammo 300 Blackout Questions
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Thread: Subsonic Ammo 300 Blackout Questions

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    Subsonic Ammo 300 Blackout Questions

    What is a good subsonic factory ammo in 300 Blackout. I have a 8.5" AR15 pistol in 300 Blackout, no suppressor. I am looking for a good subsonic load that will not go through every wall in my house and down the street into the neighbor's house. Something that is frangible, I think? I recently bought Hornady Subsonic 190 gr Sub-X, have not shot it yet and have no idea if it is the ammo I described above. If there is no such thing as subsonic frangible , please give me info on frangible ammo as well. Any info would be helpful. I don't reload and no plans to start.

    Thank you!
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    From what I've seen, a subsonic frangible is going to be very near impossible as the lower speeds don't cycle well in an AR platform. If you want to limit collateral damage then an expanding round would be preferable.
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    Look for SilentStrike 300AAC 140gr 1050 FPS Frangible

    Or for more information, check this thread out:
    Frangible Subsonic? - 300BlkTalk
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    Quote Originally Posted by Peacemakr40 View Post
    From what I've seen, a subsonic frangible is going to be very near impossible as the lower speeds don't cycle well in an AR platform. If you want to limit collateral damage then an expanding round would be preferable.
    well take this with the understanding that I am a newbie with the 300 B O.
    BUT--I am not familiar with a frangible in 300 BO, they may be out there I just haven't ran across them. as for expansion at sub sonic speeds I think it would be vey difficult to achieve this even in today modern world? again I may be wrong.
    I tried Remington 220 gr and Federal 220 grain (I think it was) 300 BO sub sonics. both operated flawlessly, was accurate but failed to lock the bolt rearward on the last round out of the magazine.
    after a bit of trial and error I found both 200 and 208, and 220 combination that did everything perfectly.
    I think my biggest problem was not having the best powder to build pressure quickly and stay at 1000 FPS or less.
    to my Understanding the 300 BO is so unstable , especially with the heavy, loooong projectiles that the likely hood of them tumbling if meeting much resistance is pretty good?
    I really kind of think of the sub sonic 300 BO as a 45 acp with a 220-230 grain projectile except with a 20-30-40 round clippy thang.
    I doubt personally if a sub sonic 300 would have a lot of penetration myself?
    I am sure some of our TRUE Savages that are more familiar with the cartridge will correct me where i stray in the wrong direction.
    Lets face it yo got more projectile than you got case with the 300 BO.
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    Last edited by olfarhors; 08-11-2019 at 10:18 AM.
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    .300BLK subs have great penetration, in that they will completely perforate just about any soft tissue target. As Olfarhors said, because of the length, when they hit something hard, they tend to go sideways, dumping all of their energy in whatever they ran into. In a body this means a rather large hole on the other side.

    But to address you worry about penetrating several of your walls and going down the street and penetrating the walls of someone else's home, and then into an innocent human....well that is just not something I believe that sub round is capable of doing. Let's take a .300BLK sub firing a 208 grain Hornady A-Max at a velocity of say 1,050 fps. At 200 yards, that bullet because of its high Ballistic Coefficient (BC) has only lost 60 fps in velocity, so it is still going 990 fps, but it has dropped 20". Now each barrier/wall it penetrates, it loses some more velocity and its drop increases. So you can see it will hit the ground and stay there at some not too distant range, and that is if it does not stick in some barrier before that. Now at home ranges of not really more than 30 feet, it will devastate a soft target, standing side by side it will even penetrate several soft targets, and you can even count on it penetrating a wall and taking out a soft target on the other side, but its velocity will quickly shed off at every instance of it hitting something, until it is no longer moving, and once it starts to tumble, it will not go far.

    If that is still too much penetration for your purpose, I would suggest 9mm subs, which will have less Sectional Density (SD), meaning less penetration, and a much lower BC, meaning it will shed velocity much faster. And unlike the .300BLK subs, you can count on these 147 grain JHP pistol bullets expanding, rather than tumbling.

    I hope that answers your question.
    Last edited by GreenWolf70; 08-11-2019 at 11:18 AM.
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    Thanks Greenwolf and everyone for the great advice. I will stick with the Hornady Subsonic 190gr Sub-X for defense loads. Yeah, Olfarhors, I like the 30 rd option too and the size of the pistol is incredible! Also, good to know that I have my Ruger 9mm PC loaded with 147 gr. JHP.

    Thanks again!
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    Just a note about commercial .300BLK sub ammo here. Those commercial rounds are made to shoot in a 16" barrel. You have an 8.5" barrel, almost half the length, so you are going to get a bit less velocity with those commercial. Most commercial sub loads are aiming for 1050 fps out of a 16" barrel, so you are probably looking at a couple of hundred less FPS. If you reload, you can push this back up to around 1,050 fps. I load a 208 grain Hornady A-Max with 10.0 grains of W296/H110 (it is the same powder) out of my 8.5" barrel and it is still not supersonic, i.e., you do not hear the boom/crack of the bullet going supersonic. I haven't chrono'd it but it is certainly subsonic in my gun, and it is accurate.

    BTW, most stores that carry W296 also carry H110 and the H110 is almost always cheaper, even though they are the same exact powder. It always helps to ask for both and purchase the cheaper one.

    If you gun is having problems with those subsonic 190 grain loads, i.e., it is short stroking, or you have to recock it to fire every time, try ammo with a heavier bullet. The problem is often getting enough gas to operate the action. Heavier bullet equals more gas pressure.
    Last edited by GreenWolf70; 08-11-2019 at 02:31 PM.
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    Battle of Wanat: 10 years ago last 13 July, 1LT Brostram was killed in combat killing the last enemy combatant in the outpost. The LT went to the point of decision and made the difference that turned the tide of the battle. The original investigation found the Bde Cmdr, the Bn Cmdr and the Co Cmdr at fault for dereliction of duty. If you want to see what a sarcastic silver star citation reads like, pull up the company commander's silver star.

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    Thanks for that info! The gun did great with Remington UMC 220gr subsonic, hollow tip. Maybe I will just stick with that load. I will shoot the Hornady 190 and report back. Thanks, Greenwolf
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    Find someone that makes ammo with Maker bullets. They make a subsonic that does expand and is proven devastating to all sorts of animals.

    Edit: Turns out Maker... Er... Makes some ammo themselves.
    Makerbullets.Com
    Last edited by stupimlico; 08-24-2019 at 04:31 PM.
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