Proof Barrel interest. .22 Cal 7 Twist

[RTH1800]

I called Proof Research today and they have quit making a 7 Twist in 22 Cal. This is the twist rate that makes the 75-80 grain bullets open up and become killers on larger critters. They said they would put the 7 Twist barrels back in the line if they received 10 orders.

I am up for 2-4. Anyone else have interest? If so post here and we can submit orders directly to Proof.

Thanks.

RTH

 

[B-P-UU]

I called Proof Research today and they have quit making a 7 Twist in 22 Cal. This is the twist rate that makes the 75-80 grain bullets open up and become killers on larger critters. They said they would put the 7 Twist barrels back in the line if they received 10 orders.

I am up for 2-4. Anyone else have interest? If so post here and we can submit orders directly to Proof.

Thanks.

RTH

What is there standard twist? 1:8?

 

[MarinePMI]

You could always just go with Carbon Six. They list two 7 twist barrels in .224" blanks (7 and 7.7)...

 

[RTH1800]

Yes, 8 is the standard now.
I have not used Carbon Six.
Proof has always been so good I hate to change now. Might look into it if this does not work out.
Thanks,
RTH

 

[Mordamer]

8 twist works great with 75-80 grain bullets. You don't need 7 twist unless going heavier than 80. That being said, I hope you get enough orders to get them to produce more 7 twist.

 

[RTH1800]

The 8 twist stabilizes the bullets well. The 7 twist kills much better due to rotational velocity. For paper shooting I would be fine with 8 twist.

 

[Mordamer]

The 8 twist stabilizes the bullets well. The 7 twist kills much better due to rotational velocity. For paper shooting I would be fine with 8 twist.

I have never heard this before. Is there any science to this assertion or just based on your personal experience?

 

[mirage98]

I have interest.

Count me in for 1.

 

[Codiekfx400]

The faster twist will turn the bullet at a higher rpm. This will result in more bullet expansion on impact. That is why he is saying it kills better.

 

[pucker]

I'm with Mordamer.

...A bullet from a 7 twist spins (at most) 1 time in 7" of travel. I don't see how an extra inch of travel required to finish ONE measly rotation in the 8 twist could possibly make any difference during its travel through an animal.

And I doubt that same 1-2 rotations while in tissue causing any type of expansion...vice going from 3000fps to 0.

I'd love to read some corroborating material...anyone have any?

 

[RTH1800]

I’m not posting to educate or influence you or anyone else. If you don’t want a barrel drive on and save bandwidth.

 

[redneckbmxer24]

Is there a discount or would it be full MSRP? If I could get one for what I pay (or better) at Stockys when they do there 10% sales I’d be interested.

 

[Nik H]

I'm with Mordamer.

...A bullet from a 7 twist spins (at most) 1 time in 7" of travel. I don't see how an extra inch of travel required to finish ONE measly rotation in the 8 twist could possibly make any difference during its travel through an animal.

And I doubt that same 1-2 rotations while in tissue causing any type of expansion...vice going from 3000fps to 0.

I'd love to read some corroborating material...anyone have any?

The bullet's RPM is 14% faster for the same MV in a 7 twist versus an 8 twist...that is not what I would call negligible

 

[Mordamer]

The bullet spins 14% faster for the same MV in a 7 twist versus an 8 twist...that is not what I would call negligible

Yes and radial acceleration is V^2/r. So the 14% faster spin actually translates to ~30% more radial force spinning the bullet apart.

 

[b6graham]

Yes and radial acceleration is V^2/r. So the 14% faster spin actually translates to ~30% more radial force spinning the bullet apart.

the thing that strikes me as odd is that proof dropped the 7 twist with the introduction of the sierra 90/95s and popularity of the 22cals now

btw. 95 SMKs out of a 22LRV from WTO. awesome

 

[Nik H]

Yes and radial acceleration is V^2/r. So the 14% faster spin actually translates to ~30% more radial force spinning the bullet apart.

Your assumption is that the higher radial force would damage the bullet?

 

[Sutherlandsd]

I'm really kind of shocked that Proof is dropping the 7 twist if I was going to drop one it would be the 8 twist.

 

[Mordamer]

Your assumption is that the higher radial force would damage the bullet?

No. I was offering more support to your claim that going from 1:8 to 1:7 is not negligible. I am not sure it makes a huge difference in animal killing but it is an interesting assertion.

 

[Gasgun]

I'm really kind of shocked that Proof is dropping the 7 twist if I was going to drop one it would be the 8 twist.

Agreed. I fail to see anything that 8 does that 7 doesn’t.

 

[RTH1800]

Yes, I am sure we can get them at below retail through a dealer. We just need a few more barrels.

 

[RTH1800]

Rather than debate the virtue of 7 vs 8 twist, let’s just focus on getting a few more orders. No one would need to pay prior to shipping and all will be sold at the lowest price possible. This would be through a dealer.

 

[Nik H]

No. I was offering more support to your claim that going from 1:8 to 1:7 is not negligible. I am not sure it makes a huge difference in animal killing but it is an interesting assertion.

Oh...sorry

I am not sure how the extra rotational speed affects the terminal ballistics either. Bullet expansion and the resulting wound cavity are affected by many variables but I can't say why rotational speed of the bullet would be one of them.

Sorry for the digression @rth1800

 

[b6graham]

Oh...sorry

I am not sure how the extra rotational speed affects the terminal ballistics either. Bullet expansion and the resulting wound cavity are affected by many variables but I can't say why rotational speed of the bullet would be one of them.

Sorry for the digression @rth1800

so if certain bullets dont expand when moving slow, wouldnt a faster twist, even with same veloity, potentially allow it to expand better?

 

[Nik H]

so if certain bullets dont expand when moving slow, wouldnt a faster twist, even with same veloity, potentially allow it to expand better?

I really don't want to deviate this thread from its intended purpose...there are other areas of the forum better suited for this discussion

 

[RTH1800]

X

 

[RTH1800]

The good side of debate is it keeps the thread alive. Go ahead. It might help.

 

[Nik H]

The good side of debate is it keeps the thread alive. Go ahead. It might help.

LOL

So to answer @b6graham

I would think that a faster rotational speed would have some effect but I haven't seen much written about it in discussions of terminal ballistics.

I don't have an intuitive reason why the wound cavity would be greater if a bullet spins faster unless the shock wave is greater due to the larger radial force

 

[sgtsmmiii]

I'd be in for one.

BTW, I agree on the rotational velocity on critter impacts. It's visibly evident on PD's when the the bullets are spun at 8 twists versus 12 ( .223's ). They come apart WAY more violently. Count me among the convinced.

 

[Nik H]

I'd be in for one.

BTW, I agree on the rotational velocity on critter impacts. It's visibly evident on PD's when the the bullets are spun at 8 twists versus 12 ( .223's ). They come apart WAY more violently. Count me among the convinced.

That is an interesting observation...

So what you are saying is the that bullet disintegrates more readily than when shot out of a lower twist rate barrel. This makes some sense as the more violent fragmentation would cause a greater wound channel.

I have several papers on the terminal ballistic characteristics of the .22 caliber (5.56) round but none speak of this in a direct fashion.

 

[RTH1800]

If 8 twist was better Crane would have used them on MK12.

 

[RTH1800]

Rotational velocity is near constant over entire bullet flight.
Centrifical force is very strong.
The 8 twist pleases no one. Neither is much good for bullets under 55 grains and 7 is better for 55 and up. They dropped the wrong barrel.
Most or all of the high BC BULLETS will shoot better with 7 twist.

 

[Nik H]

Rotational velocity is near constant over entire TOF

I agree that rotational velocity is lost to a much less of a degree than linear velocity but it does definitely drop. It will be more pronounced for longer TOF.