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Posted: 8/29/2026 2:41:03 PM EDT
[Last Edit: 308223][Edited]
| What is the optimum barrel length and twist for a 300 blackout? I would be reloading for 130 gr and 190 gr projectiles. What powder? 16" barrel? or shorter? I want to optimize the powder burn so an added suppressor won't gas me to death. I do apologize if this has been discussed before and I haven't read it. Could you refer me to that thread? |
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Originally Posted By 308223: What is the optimum barrel length and twist for a 300 blackout? I would be reloading for 130 gr and 190 gr projectiles. What powder? 16" barrel? or shorter? I want to optimize the powder burn so an added suppressor won't gas me to death. I do apologize if this has been discussed before and I haven't read it. Could you refer me to that thread? https://www.ar15.com/forums/armory/300-Blackout-Master-Thread/42-385765/ Here you go. |
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I’ll chime in with a bit more context. Optimum means different things depending on what you’re looking for. Subs to great out of 8-9 inch barrels, and this is close to the barrel length that AAC used in developing the round. But if you want 7.62x39-class results, you need a longer barrel, and of course drastically different loads. I haven’t bothered with subs because I couldn’t afford a can - which may be changing, but that’s beside the point. But my supers, with bullets ranging from 110gr to 150gr, have done much better out of a 16 inch barrel than an 8 inch barrel. And it’s more than “dang that’s loud!”. They benefited from better accuracy as well. |
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If all you ever really plan on shooting is subs? Then a 10"ish barrel is good enough. If you want the ability to actually shoot supers at a good velocity? 14.5 or 16". Just make sure you get a pistol length gas system so subs cycle correctly. Also bear in mind? A 300 BO is slightly edged out in supersonic performance by about 5-10% velocity by a 7.62x39 even with a 16" barrel. |
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https://www.scribd.com/document/405487527/300-Blk-Whitepaper Everything you need to make intelligent observations / decisions about 300 blackout is in Rob Silvers (former AAC) 2011 pitch slides. H110 / W296 is generally preferred for supersonics in the 110-120 grain area. Accurate 1680 works well for subsonics & 150 grain .308-bulk-bullet plinker / trash loads. Lil Gun can make quiet subs but burns hot and can deposit copper & lead more than cooler powders. |
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Originally Posted By KalmanPhilter: https://www.scribd.com/document/405487527/300-Blk-Whitepaper Everything you need to make intelligent observations / decisions about 300 blackout is in Rob Silvers (former AAC) 2011 pitch slides. H110 / W296 is generally preferred for supersonics in the 110-120 grain area. Accurate 1680 works well for subsonics & 150 grain .308-bulk-bullet plinker / trash loads. Lil Gun can make quiet subs but burns hot and can deposit copper & lead more than cooler powders. Look forward to reading that! Thanks! |
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