224 Valkyrie Barrel Twist

[TORCHRIDER]

I am impressed enough with the 224 Valkyrie that I want to build one on the AR15 platform.

However, I have some questions regarding barrel twist.

I am torn between ordering a 7 twist barrel that is available now versus waiting for a 6.5 or 6 twist in a few months.

I know the 6 or 6.5 will likely stabilize the longer 90/95 grainers from Sierra as well as some heavier/longer designs not yet released, but will a 6 or 6.5 twist be too fast for bullets like 69/75/77/80 grainers? Are they so fragile that many wont even make it to the target? I assume anything in the 55 grain territory will be toast?

So.....I am guessing I am going to need to make a decision on one of two ways to go:

1. 7 twist to handle everything from 55 to 80 grains. Maybe 90's?
2. 6 or 6.5 to handle everything from 80 to 100 grains. Maybe 77's?

Is my logic sound or am I out in left field? I appreciate feedback from y'all on this.

 

[cmillard]

Well, an old high power shooter friend of mine has a medeesha space gun with a 6.5 twist barrel. He said he couldnt get 90s to shoot in it but 80 grainers (sierra) worked fine. He didn't know why the 90s wouldnt shoot.

 

[JASmith]

Go with the fast twist to accomodate bullet weights the Valkyrie is designed for.

With the lighter bullets, accuracy should remain good in spite of faster than optimum RPM.

There is also the chance that the lightest bullets loaded to max velocity will give one entertaining leaf puffballs. One can the either back of on charge weight to find an accuracy node or run wiyth heavier bullets.

 

[5screw]

The 1:7 is supposed to be enough because of the increased velocity over .223, meaning increased speed of rotation. I think it's the rotation over time not distance that counts for gyroscopic stability. Anyway, White Oak is building its 224 Valkyrie uppers with 1:7 Kriegers for shooting the 90 grain load. Bought one yesterday so I hope 1:7 is right! About the 80 gr bullets, my 1:7 20" service rifle barrels shoot 80 gr smk's really well. 6.5 is an awfully fast twist, might make lighter bullets bust.

 

[5screw]

The 1:7 is supposed to be enough because of the increased velocity over .223, meaning increased speed of rotation. I think it's the rotation over time not distance that counts for gyroscopic stability.....


UPDATE: Just FYI, I have my 224V upper on order and White Oak had me increase the twist to 6.5:1 for shooting the 90's.

 

[Rodney]

The 1:7 is supposed to be enough because of the increased velocity over .223, meaning increased speed of rotation. I think it's the rotation over time not distance that counts for gyroscopic stability. Anyway, White Oak is building its 224 Valkyrie uppers with 1:7 Kriegers for shooting the 90 grain load. Bought one yesterday so I hope 1:7 is right! About the 80 gr bullets, my 1:7 20" service rifle barrels shoot 80 gr smk's really well. 6.5 is an awfully fast twist, might make lighter bullets bust.

I have heard many people say the Valkyrie’s increased speed will stabilize the 90’s in a 1 and 7 twist. Most data out is claiming 2700 to 2750 FPS for the Valkyrie with the 90 grain match king. Won’t most 223’s do that or better. Now I’m aware that’s not at magazine length of course which the Valkyrie can do. If I’m not mistaken most guys running 223’s with the 90’s are running a 6.5 to 1 twist. That would be my choice. I see your updated post 5screw and think you made the best choice going with the faster twist.

 

[Ray123]

I am impressed enough with the 224 Valkyrie that I want to build one on the AR15 platform.

However, I have some questions regarding barrel twist.

I am torn between ordering a 7 twist barrel that is available now versus waiting for a 6.5 or 6 twist in a few months.

I know the 6 or 6.5 will likely stabilize the longer 90/95 grainers from Sierra as well as some heavier/longer designs not yet released, but will a 6 or 6.5 twist be too fast for bullets like 69/75/77/80 grainers? Are they so fragile that many wont even make it to the target? I assume anything in the 55 grain territory will be toast?

So.....I am guessing I am going to need to make a decision on one of two ways to go:

1. 7 twist to handle everything from 55 to 80 grains. Maybe 90's?
2. 6 or 6.5 to handle everything from 80 to 100 grains. Maybe 77's?

Is my logic sound or am I out in left field? I appreciate feedback from y'all on this.

I run 6.5 twist shoot 95 SMK and 88 ELD-M mostly...24" barrel RL-17.

 

[shooter308]

I have one of each in 7 twist and 6.5 twist and the 7 twist shoots the 90s better . My 7 twist barrel is a Rainier Arms ultra match 24" and has been awesome .

 

[PracticalTactical]

I have heard many people say the Valkyrie’s increased speed will stabilize the 90’s in a 1 and 7 twist. Most data out is claiming 2700 to 2750 FPS for the Valkyrie with the 90 grain match king. Won’t most 223’s do that or better. Now I’m aware that’s not at magazine length of course which the Valkyrie can do. If I’m not mistaken most guys running 223’s with the 90’s are running a 6.5 to 1 twist. That would be my choice. I see your updated post 5screw and think you made the best choice going with the faster twist.

I run 90s in my bolt action 223 with a 1:7 with no problem at all. It's got a long throat so I run at between 2850 -2900 FPS depending on if the brass was fired before.

The challenge for you AR15 guys is the short round length. The bearing surface is way inside the case, so the free bore cannot align the bullet to the rifling.

My OAL is around 2.650, but to feed from a AR mag you gotta be under 2.300". That costs you with both speed and bullet alignment.

I'm pretty confident you can hit the velocity you need to get stable, but the limiting factor for short rounds is how you align the bullet to the rifling.

It would be super cool if they made the AR10 in 224 Valk, then you could run the heavies from a 308 length mag with bullets seated way out.