What are the barrel twist rates for 556 and 300blk? I’m hoping for a fast twist rate option for 300 like 1in5. Any hope?
it’s like 1/7 1/8 1/9 for optimal twist on a 5.56, and for a .300blk its like 1/12 if memory serves right.
I am also hoping for a 1:5 for the 300 blackout.
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well im probably way wrong on the 300 blackout twist, so please dont take my post to the bank.
Definitely off on .300BLK twist. 1:8 is a slow twist that may or may not stabilize 220gr subsonic loads. 1:7 typically will stabilize 220gr subs running at ≈1050fps, but it takes roughly an 8-9” barrel to get to 1050fps without running into signs of overpressure. That’s why guys running <7” barrels want something like 1:5 or 1:6” twist. Keep in mind that stability is based around the rpm the projectile is turning, and that is a function of muzzle velocity and twist rate. Lower muzzle velocity means faster twist is needed to achieve the same rotational speed. A 5” barrel .300BLK may only achieve 800-900fps with a 220gr projectile before signs of overpressure rear their ugly head. Sure, a guy can drop back to a shorter lighter sub in the 194gr class to get velocity back up and require less rpm for stability, but that’s giving up choices in subsonic ammo selection. Hope this helps you understand the basics of why guys want a 1:7 or faster twist for .300BLK. As a caveat, something as slow as 1:12 twist would likely be more ideal for someone only interested in 125gr or lighter supersonic .300BLK loads, but that effectively neuters the versatility of .300BLK. .300BLK also is not such a high velocity round for over spinning supersonic loads to be much of an issue.
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Ditto!
300 Blackout needs to spin fast, especially subs
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Would it be too much to ask for a .300 option of about 1:3 twist so we can investigate the effect, if any, of the “8.3mm Effect” on .300 Blackout?
I know that 110-grain JHP with thin jackets designed for .30 Carbine are literally ripped apart when loaded to maximum velocities from the 1:10 twist of a .30-06. But that’s okay, because the .300 Blackout won’t achieve the same velocities and has provided us with a plethora or stronger 110-grain projectiles as well.
Welcome to the forum!!
