224 Valkyrie Bullet Choices for 6.5 Twist Barrel

[Far North Hunter]

Looking for feedback on results from shooters who are running a 6.5 twist barrel on their Valkyrie. I have both 75 and 80 grain Hornady ELD Match on the shelf, as well as Sierra 77 grain SMK. In checking bullet base to give it looks I'd have to seat the bullets quite deep in the case versus the Hornady. Question, will the 6.5 twist stabilize bullets in the weight mentioned, or do you have a bullet recommendation based on experience.

 

[Peter Morton]

Bullet stability is more dependent on the length of the bullet than the weight. And a 6.5" twist will stabilize all of the bullets you mentioned. You can check stuff like that here:

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[RegionRat]

A 6.5 twist is pretty far up the scale of being a really fast twist for a 22 caliber bullet.

At some point, the rotation of the bullet (RPM) creates a centrifugal force that can distort the bullet. At some RPM rates, bullets can even disintegrate.

The 1:6.5 isn't common in 224. It exists mostly to serve F-T/R and folks who are wanting to push 85.5 and 90 gr bullets, but even there you have to watch out for issues with very high RPM rates if the velocity is also high.

The simple version is RPM = Muzzle Velocity x 720/twist

For example a 224V pushing a 90 grain at 2650 fps with a 7 twist will be (2650x(720/7))= 272,571 RPM and has an SG of 1.35 so it gives up about 4% on the BC.
The same 224V at a 6.5 Twist will be 293,539 RPM with an SG of 1.56

The question to ask is if the bullet will distort or blow up at 294k RPM? If you had to, you could back off and it would still be stable.

Some manufacturers will answer those questions over the phone and know the rough limits of their bullets. I would give them a ring.

Good Luck and in for the range report.

 

[Rosebud]

I'm loading for a guy now who has a 1 in 7 twist. We started with Hammer Hunter in 52 grain that shot good. But we are going with the 64 grain Hammer To make use of the fast twist. I ran into pressure at 3500 with the 52 no matter what powder I used. Tried 5 of them. Really thought I could get. 3600. Book was showing 3500 + with C and C bullets thought another100 with hammers was doable. Waiting on.components for the 64s. Hammers are long bullets, The 64 is equally the size of 90 grain cup and core bullet. We will see how it works out. He really wants to hunt deer sized game with it. I don't think we will run into distortion with the hammers. This is the first time to load the Valk. And a twist this fast. Any thoughts to help will be appreciated.

 

[Far North Hunter]

A 6.5 twist is pretty far up the scale of being a really fast twist for a 22 caliber bullet.

At some point, the rotation of the bullet (RPM) creates a centrifugal force that can distort the bullet. At some RPM rates, bullets can even disintegrate.

The 1:6.5 isn't common in 224. It exists mostly to serve F-T/R and folks who are wanting to push 85.5 and 90 gr bullets, but even there you have to watch out for issues with very high RPM rates if the velocity is also high.

The simple version is RPM = Muzzle Velocity x 720/twist

For example a 224V pushing a 90 grain at 2650 fps with a 7 twist will be (2650x(720/7))= 272,571 RPM and has an SG of 1.35 so it gives up about 4% on the BC.
The same 224V at a 6.5 Twist will be 293,539 RPM with an SG of 1.56

The question to ask is if the bullet will distort or blow up at 294k RPM? If you had to, you could back off and it would still be stable.

Some manufacturers will answer those questions over the phone and know the rough limits of their bullets. I would give them a ring.

Good Luck and in for the range report.

I'm loading for a guy now who has a 1 in 7 twist. We started with Hammer Hunter in 52 grain that shot good. But we are going with the 64 grain Hammer To make use of the fast twist. I ran into pressure at 3500 with the 52 no matter what powder I used. Tried 5 of them. Really thought I could get. 3600. Book was showing 3500 + with C and C bullets thought another100 with hammers was doable. Waiting on.components for the 64s. Hammers are long bullets, The 64 is equally the size of 90 grain cup and core bullet. We will see how it works out. He really wants to hunt deer sized game with it. I don't think we will run into distortion with the hammers. This is the first time to load the Valk. And a twist this fast. Any thoughts to help will be appreciated.

In a 7 twist I'm shooting 77 gr Sierra BTHP. Over CFE 223. It will do minute of dime. Have not worked, in a gas gun. In my gas gun. In a 8 twist bolt it prefers 55-60 gr.

 

[RegionRat]

This is the first time to load the Valk. And a twist this fast. Any thoughts to help will be appreciated.

You mentioned 1:7 twist, is that right?
For that long 64 Hammer bullet, here is what they recommend.

Ambient pressure (altitude) plays a role in stability. The higher you are, the easier it gets because the average pressure is lower and that makes for less dense air flow to destabilize the bullet. You are doing better than their recommended 1:8.5 so you should be fine.

If you have the bullet dimensions, it isn't difficult to run the SG numbers. Just keep in mind those are not real hard stability calculations so take them with a grain of salt.... You would like to run a SG of 1.5 or just a little higher, but if you drop under 1.5 it isn't instant death.

If you were running below SG 1.5, you have less margin and some of the shots may act like they have a worse BC value, some may not. Take that number closer to SG 1.0 and you will almost certainly see poor performance or even tumbling. Those ones in the grey zone of say SG1.25 - 1.35 often give a poor vertical performance at distance because some will wobble and some will not.

Here is their 1:8.5 at sea level and MV 2650,

And here is your 1:7

 

[Far North Hunter]

You mentioned 1:7 twist, is that right?
For that long 64 Hammer bullet, here is what they recommend.

View attachment 460087


Ambient pressure (altitude) plays a role in stability. The higher you are, the easier it gets because the average pressure is lower and that makes for less dense air flow to destabilize the bullet. You are doing better than their recommended 1:8.5 so you should be fine.

If you have the bullet dimensions, it isn't difficult to run the SG numbers. Just keep in mind those are not real hard stability calculations so take them with a grain of salt.... You would like to run a SG of 1.5 or just a little higher, but if you drop under 1.5 it isn't instant death.

If you were running below SG 1.5, you have less margin and some of the shots may act like they have a worse BC value, some may not. Take that number closer to SG 1.0 and you will almost certainly see poor performance or even tumbling. Those ones in the grey zone of say SG1.25 - 1.35 often give a poor vertical performance at distance because some will wobble and some will not.

Here is their 1:8.5 at sea level and MV 2650,
View attachment 460088

And here is your 1:7
View attachment 460089

Yes, 7 twist.

 

[Peter Morton]

I have a 6.5" twist and ordered the 75G Absolute Hammer. I could not get a powder load and seating depth that would give me an OAL that fit the magazine. At least, not with powders I had on hand. Steve at Hammer Bullets was very kind in taking them back to exchange for other product. I'm still considering what bullet to load. I'm about settled on the 69 Grain 224. I've just got to find powder. I doubt the Hammers will have any problems with the fast twist.