300 Blackout Barrel Twist

[alamo5000]

I have been doing some research and they now have 300BLK barrels in much faster twist rates. Up to just a few years ago 1:8 or 1:7 was the main go to for manufacturing. Now though there's a few 1:5 twist on the market.

I loosely know the back story, IE, Q and Kevin B introduced the faster twist, and claimed more rotational energy is better in certain situations. Also, and this is my main take, that it makes even shorter barrels viable options. If I'm not mistaken even Sig has factory options using 1:5 twist rates. If you are shooting a 5" barrel it seems like that twist would probably help make that possible for stability and your suppressor's sake.

If you have any experience with that subject, or if you know of videos, blogs, tests, etc please feel free to post it below. I'm in learning mode so share what you got.

 

[Ape_Factory]

Twist rate is more for the bullet's OAL in relation to stability. The longer the bullet, the faster the twist rate needed to stabilize it. A 1:7 twist will stabilize any bullet you'd want to stuff in a 300 blackout case. Bullet stability has nothing to do with barrel length other than having enough length to get the bullet up to speed as the powder burns down the length of the barrel. But even subsonic rounds are stable until they slow down enough to start to wobble. But it won't matter if a bullet leaves from a 6" barrel at 900fps or a 9" barrel at 900fps.

The 1:5 rate is strictly marketing BS and on something like Sig's 9" barrel, will require solid projectiles over bonded bullets (more $$$) for the lighter stuff as it'll be easy to get the velocity beyond the bonded bullet's rpm limit. On the 6.75" barrel, it'll be much harder, if not impossible to get the rpm up enough with 110 grain pills and supersonic loads to cause jacket separation. Can get there quite easily in the 9" version.

I own the 9" version and have contemplated purchasing the shorter upper just so I can shoot cheap(er) supers but Sig's not getting any more money at this point and I'd rather spend more on projectiles and have the velocity advantage of a 9" barrel with supers. With that said, if someone offered a 1:7 twist replacement barrel, I'd buy one in a heartbeat.

 

[wvfarrier]

Stick with 1-7, it will do 100gr to 240gr with no issues

 

[SBRSarge]

Stick with 1-7, it will do 100gr to 240gr with no issues

Gospel, this is!